US20220330869A1 - Dual-helmet magnetoencephalography apparatus - Google Patents
Dual-helmet magnetoencephalography apparatus Download PDFInfo
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- US20220330869A1 US20220330869A1 US17/853,769 US202217853769A US2022330869A1 US 20220330869 A1 US20220330869 A1 US 20220330869A1 US 202217853769 A US202217853769 A US 202217853769A US 2022330869 A1 US2022330869 A1 US 2022330869A1
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Images
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- A—HUMAN NECESSITIES
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- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
- A61B5/242—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents
- A61B5/245—Detecting biomagnetic fields, e.g. magnetic fields produced by bioelectric currents specially adapted for magnetoencephalographic [MEG] signals
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/40—Detecting, measuring or recording for evaluating the nervous system
- A61B5/4058—Detecting, measuring or recording for evaluating the nervous system for evaluating the central nervous system
- A61B5/4064—Evaluating the brain
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- A—HUMAN NECESSITIES
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- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6802—Sensor mounted on worn items
- A61B5/6803—Head-worn items, e.g. helmets, masks, headphones or goggles
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- A—HUMAN NECESSITIES
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- A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/007—Environmental aspects, e.g. temperature variations, radiation, stray fields
- G01R33/0076—Protection, e.g. with housings against stray fields
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/035—Measuring direction or magnitude of magnetic fields or magnetic flux using superconductive devices
- G01R33/0354—SQUIDS
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/323—Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR
- G01R33/326—Detection of MR without the use of RF or microwaves, e.g. force-detected MR, thermally detected MR, MR detection via electrical conductivity, optically detected MR involving a SQUID
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/32—Excitation or detection systems, e.g. using radio frequency signals
- G01R33/34—Constructional details, e.g. resonators, specially adapted to MR
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2029—Modifications to facilitate cooling, ventilating, or heating using a liquid coolant with phase change in electronic enclosures
- H05K7/20318—Condensers
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2039—Modifications to facilitate cooling, ventilating, or heating characterised by the heat transfer by conduction from the heat generating element to a dissipating body
- H05K7/20436—Inner thermal coupling elements in heat dissipating housings, e.g. protrusions or depressions integrally formed in the housing
- H05K7/20445—Inner thermal coupling elements in heat dissipating housings, e.g. protrusions or depressions integrally formed in the housing the coupling element being an additional piece, e.g. thermal standoff
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- A—HUMAN NECESSITIES
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- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0223—Magnetic field sensors
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- A—HUMAN NECESSITIES
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- A61B2562/04—Arrangements of multiple sensors of the same type
- A61B2562/046—Arrangements of multiple sensors of the same type in a matrix array
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- A—HUMAN NECESSITIES
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- A61B2562/18—Shielding or protection of sensors from environmental influences, e.g. protection from mechanical damage
Definitions
- the present disclosure relates to a magnetoencephalography apparatus and, more particularly, to a magnetoencephalography apparatus provide with dual helmets.
- a magnetoencephalography apparatus is an apparatus for measuring magnetic signals generated by microcurrent of cerebral neural circuits, and is used to study brain functions and to diagnose functional brain diseases.
- a magnetoencephalography signal has an amplitude of 10 fT to 1 pT and has a frequency of 0.1 to 1 kHz. Accordingly, there is a requirement for a magnetic sensor having improved sensitivity and a technology to cancel environmental magnetic noise.
- a magnetic sensor which is most advantageous in practical terms is a superconducting quantum interference device (SQUID) based on a low-temperature superconductor niobium (Nb).
- Nb used for a low-temperature superconducting SQUID has a critical temperature of 9 K
- cooling using liquid helium or a low-temperature freezer is required.
- Current magnetoencephalography apparatuses need to supplement liquid helium. Optimization of a structure, a thickness, and an installing method of a material is required to reduce thermal magnetic noise, caused by a superinsultion and thermal shield installed in a Dewar vacuum portion, while reducing an evaporation rate of a Dewar.
- helium gas tends to easily pass through a small gap
- high density of glass fiber reinforced plastics, used as a material of the Dewar is required.
- a pick-up coil and a SQUID sensor are disposed to be maintained in a vacuum state. Accordingly, only a low-temperature refrigerant is present in an internal helium storage container for storing a liquid refrigerant. Accordingly, there is only a path to fill the refrigerant. Accordingly, a diameter of a neck portion of the internal helium storage container may be significantly reduced. As a result, an evaporation rate of the liquid refrigerant may be reduced.
- An aspect of the present disclosure is to provide a coil-in-vacuum and dual-helmet structure, capable of measuring both adults and children in a single magnetoencephalography apparatus measuring device.
- Another aspect of the present disclosure is to provide a cooling apparatus having a dual-wall structure, capable of blocking radiant heat.
- Another aspect of the present disclosure is to provide a coolant tube structure having a coaxial dual-tube structure, capable of providing a rotational motion of a Dewar.
- Another aspect of the present disclosure is to provide a cooling device, capable of recycling a refrigerant.
- Another aspect of the present disclosure is to provide a magnetoencephalography measuring apparatus including two helmets.
- a dual-helmet magnetoencephalography measuring apparatus includes: an internal container storing a liquid refrigerant; an external container disposed to surround the internal container and including a first external helmet and a second external helmet disposed to be spaced apart from each other; a first sensor-mounted helmet disposed to surround the first external helmet between the external container and the internal container; a second sensor-mounted helmet disposed to surround the second external helmet between the external container and the internal container; a plurality of first SQUID sensor module disposed on the first sensor-mounted helmet; and a plurality of second SQUID sensor module disposed on the second sensor-mounted helmet.
- a space between the external container and the internal container is in a vacuum state.
- the external container may branch off in the form of T.
- the external container may include a first branch and a second branch branching off from a cylindrical external container body portion in the form of T.
- Each of the first external helmet and the second external helmet may be coupled to the first branch and the second branch, respectively.
- the first external helmet and the second external helmet may face each other and may have different sizes.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a rotational motion unit rotating the internal container and the external container about a central axis of the rotational motion unit.
- the internal container may include: a neck portion into which a baffle insert is inserted; and an internal body portion having an increased diameter as compared with the neck portion.
- the neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- the neck portion may further include a heat shielding layer disposed between the internal cylinder and the external cylinder.
- the internal cylinder may further include a plurality of ring projections protruding outwardly of the internal cylinder.
- Thermal anchors may be coupled to the ring projections, respectively.
- the ring projections may be disposed to be spaced apart from each other.
- the external cylinder may be separated with the ring projection interposed therebetween.
- an external circumferential surface of the ring projection and an internal circumferential surface of the thermal anchor may be screw-coupled to each other.
- the thermal anchor may include a cylindrical thermal anchor coupling portion and a disc-shaped thermal anchor body portion disposed on an external circumferential surface of the thermal anchor coupling portion.
- An internal circumferential surface of the thermal anchor coupling portion may be screw-coupled to an external circumferential surface of the ring projection.
- the internal container may include: a neck portion into which a baffle insert is inserted; and a body portion having a diameter increased as compared to the neck portion.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporated refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant; and a condenser connected to the refrigerant exhaust tube and the refrigerant injection tube and condensing an evaporated refrigerant exhausted through the refrigerant injection tube.
- the refrigerant injection tube may have a coaxial structure inserted into the refrigerant exhaust tube.
- each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a C-shaped external container support portion supporting lower surfaces of the first branch and the second branch; and a rotational motion unit coupled to the external container support portion to provide a rotational motion to the external container.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a vacuum-sealing portion inserted into a through-hole formed in the lower surface of each of the first and second branches to seal signal lines and disposed inside the external container support portion; and a signal line connection box disposed below the external container support portion and connecting the signal lines, sealed through the vacuum-sealing portion, to each other.
- the rotational motion unit may further include: an upper base box disposed to surround the signal line connection box; a lower base box disposed below the upper base box; and a bearing portion disposed between the upper base box and the lower base box to provide a rotational motion to the upper base box.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a handle coupled to an external side of the upper base box.
- the first external helmet may include a coupled portion provided with a long groove.
- the first external helmet may be coupled to one end of the first branch while rotating along the long groove in an aligned state.
- the second external helmet may include a coupled portion provided with a long grove.
- the second external helmet may be coupled to one end of the second branch while rotating along the long groove in an aligned state.
- the internal container may include: a neck portion into which a baffle insert is inserted; a first body portion having an increased diameter as compared with the neck portion; a second body portion having an increased diameter as compared with the first body portion; and a third body portion having a decreased diameter as compared with the second body portion.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a pair of first support portions coupled to an interface between the neck portion and the first body portion and respectively extending in a direction of the first external helmet and a direction of the second external helmet; a pair of second support portion coupled to an interface between the first body portion and the second body portion and respectively extending in the direction of the first external helmet and the direction of the second external helmet; a pair of third support portion coupled to an interface between the second body portion and the third body portion and respectively extending in the direction of the first external helmet and the direction of the second external helmet; a first fixing ring coupled to the first, second, and third support portions in the direction of the first external helmet; a second fixing ring coupled to the first, second, and third support portion in the direction of the second external helmet; a first auxiliary fixing part connecting the first fixing ring and the first sensor-mounted helmet; and a second auxiliary fixing part connecting the second fixing ring and the second senso-mounted helmet.
- each of the first, second, and third support portions may include a plurality of arc long grooves.
- a coupling member may be inserted into each of the arc long grooves to be coupled to the internal container.
- the first sensor-mounted helmet may include: a helmet body having an open region for securing a view; a lower brim disposed along an edge of a lower surface of the helmet body; an upper brim providing a brim in the open portion of the helmet body; a helmet fixing ring having a ring shape at a predetermined interval from the lower brim and continuously connected to the upper brim; and a plurality of connection pillars vertically connecting the lower brim and the upper brim to each other.
- the dual-helmet magnetoencephalography measuring apparatus may further include: a first auxiliary thermal anchor disposed on a lower surface of each of the upper brim and the lower brim of the first sensor-mounted helmet; a first internal 4K heat shielding portion being in thermal contact with the first auxiliary thermal anchor and disposed on an internal side surface of the first sensor-mounted helmet; and a first external 4K heat shielding portion being in thermal contact with the first auxiliary thermal anchor and disposed on an external side surface of the first sensor-mounted helmet.
- the first auxiliary thermal anchor, the first internal 4K heat shielding portion, and the first external 4K heat shielding portion may be in thermal contact with a main thermal anchor by a litz wire.
- each of the plurality of first SQUID sensor modules may be in thermal contact with a main thermal anchor disposed on a lower surface of the internal container through a litz wire.
- Each of the plurality of second SQUID sensor modules may be in thermal contact with the main thermal anchor disposed on the lower surface of the internal container through a litz wire.
- the first SQUID sensor modules may be cooled by a plural of litz wires. Some of the plurality of litz wires may be connected to first SQUID sensor modules arranged around the first SQUID sensor module, and the remainder of the plurality of litz wires may be in thermal contact with a main thermal anchor.
- the first SQUID sensor module may be cooled by six litz wires.
- the six litz wires two litz wires may be in thermal contact with the main thermal anchor, and four litz wires may be connected to the first SQUID sensor modules arranged around the first SQUID sensor module.
- the internal container may include a neck portion into which a baffle insert is inserted.
- the neck portion may have a double-wall structure.
- Washer-shaped first to third thermal anchors, disposed to be vertically spaced apart from each other, may be provided on an external side of the neck portion.
- the first thermal anchor may be connected to a 120K heat shielding layer.
- the second thermal anchor may be connected to an 80K heat shielding layer.
- the third thermal anchor may be connected to a 40K heat shielding layer.
- the 40K heat shielding layer may be disposed to surround the first sensor-mounted helmet and the second sensor-mounted helmet.
- the first SQUID sensor module may be inserted into a through-hole, formed in the first sensor-mounted helmet, to be fixed.
- the first SQUID sensor module may include a plurality of holes. Litz wires may be respectively inserted into the holes to cool a SQUID sensor.
- the main thermal anchor may include: a first heat transfer unit formed of oxygen-free copper and including a first disc, a first upper projection protruding from a central axis of the first disc to an upper surface of the first disc, and a first lower projection protruding from the central axis of the first disc to a lower surface of the first disc; a second heat transfer unit formed of oxygen-free copper and including a second disc, a second upper projection protruding from a central axis of the second disc to an upper surface of the second disc, and a second lower projection protruding from the central axis of the second disc to a lower surface of the second disc; a third heat transfer unit formed of oxygen-free copper and including a third disc, a third upper projection protruding from a central axis of the third disc to an upper surface of the third disc, and a third lower projection protruding from the central axis of the third disc to a lower surface of the third disc; a fourth heat transfer unit formed of oxygen-free copper and
- the second upper projection of the second heat transfer unit may be provided with a groove for coupling to the first lower projection of the first heat transfer unit.
- the second lower projection of the second heat transfer unit may be provided with a groove for coupling to the third upper projection of the third heat transfer unit.
- the third lower projection of the third heat transfer unit may be provided with a groove for coupling to the fourth upper projection of the fourth heat transfer unit.
- the first thermal expansion control unit may include: a first insulating body portion having the same diameter as a first diameter of the first disc; a second insulating body portion embedded in a lower surface of the internal container and having a second diameter greater than the first diameter; and a third insulating body portion having a third diameter smaller than the second diameter.
- the third insulating body portion may be disposed to surround an external circumferential surface of the second disc.
- a magnetic field measuring apparatus includes: an external container; and a cylindrical internal container storing a liquid refrigerant and inserted into the external container.
- the internal container includes: a neck portion into which a baffle insert is inserted; and a body portion having an increased diameter as compared with the neck portion.
- the neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- the internal cylinder may further include a plurality of ring projections protruding outwardly of a cylinder.
- Thermal anchors may be coupled to the ring projections, respectively.
- the ring projections may be disposed to be spaced apart from each other.
- the external cylinder may be separated with the ring projection interposed therebetween.
- the neck portion may further include a heat shielding layer disposed between the internal cylinder and the external cylinder.
- an external circumferential surface of the ring projection and an internal circumferential surface of the thermal anchor may be screw-coupled to each other.
- each of the thermal anchors may include a disc-shaped thermal anchor body portion disposed on both a cylindrical thermal anchor coupling portion and on an external circumferential surface of the thermal anchor coupling portion.
- An internal circumferential surface of the thermal anchor coupling portion may be screw-coupled to an external circumferential surface of the ring projection.
- the thermal anchors may include first to third thermal anchors.
- the first thermal anchor may be connected to a 120K heat shielding layer
- the second thermal anchor may be connected to an 80K heat shielding layer
- the third thermal anchor may be connected to a 40K heat shielding layer.
- the magnetic field measuring apparatus may further include: a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporate refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant;
- the refrigerant injection tube may provide a coaxial structure to be inserted into the refrigerant exhaust tube.
- Each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- a magnetic field measuring apparatus include: an external container; a cylindrical internal container storing a liquid refrigerant and inserted into the external container; a baffle inserted into the internal container; a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporated refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant; and a condenser connected to the refrigerant exhaust tube and the refrigerant injection tube and condensing an evaporate refrigerant exhausted through the refrigerant injection tube.
- the refrigerant injection tube may have a coaxial structure inserted into the refrigerant exhaust tube.
- Each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- the internal container may include: a neck portion where the baffle is inserted; and a body portion having an increased diameter as compared with the neck portion.
- the neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- a magnetic field measuring apparatus include: an external container; a cylindrical internal container storing a liquid refrigerant and inserted into the external container; a main thermal anchor disposed on a lower surface of the internal container; and a plurality of first SQUID sensor modules disposed on an external side of the internal container.
- Each of the plurality of first SQUID sensor modules may be in thermal contact with a main thermal anchor, disposed on a lower surface of the internal container, through a litz wire.
- the main thermal anchor may include: a first heat transfer unit formed of oxygen-free copper and including a first disc, and a first lower projection protruding from the central axis of the first disc to a lower surface of the first disc; a second heat transfer unit formed of oxygen-free copper and including a second disc, a second upper projection protruding from a central axis of the second disc to an upper surface of the second disc, and a second lower projection protruding from the central axis of the second disc to a lower surface of the second disc; a third heat transfer unit formed of oxygen-free copper and including a third disc, a third upper projection protruding from a central axis of the third disc to an upper surface of the third disc, and a third lower projection protruding from the central axis of the third disc to a lower surface of the third disc; a fourth heat transfer unit formed of oxygen-free copper and including a fourth disc, a fourth upper projection protruding from a central axis of the fourth
- the second upper projection of the second heat transfer unit may be provided with a groove for coupling to the first lower projection of the first heat transfer unit.
- the second lower projection of the second heat transfer unit may be provided with a groove for coupling to the third upper projection of the third heat transfer unit.
- the third lower projection of the third heat transfer unit may be provided with a groove for coupling to the fourth upper projection of the fourth heat transfer unit.
- the first thermal expansion control unit may include: a first insulating body portion having the same diameter as a first diameter of the first disc; a second insulating body portion embedded in a lower surface of the internal container and having a second diameter greater than the first diameter; and a third insulating body portion having a third diameter smaller than the second diameter.
- the third insulating body portion may be disposed to surround an external circumferential surface of the second disc.
- FIG. 1 is a conceptual diagram illustrating a magnetoencephalography measuring apparatus according to an example embodiment of the present disclosure.
- FIG. 2 is a perspective view illustrating a magnetoencephalography measuring apparatus.
- FIG. 3 is a cross-sectional view taken along line A-A′ in FIG. 2 .
- FIG. 4 is a perspective view illustrating an internal container and a sensor-mounted helmet.
- FIG. 5 is an exploded perspective view illustrating a rotational motion unit supporting an external container and providing a rotational motion.
- FIG. 6 is an enlarged cross-sectional view of the internal container of the magnetoencephalography measuring apparatus.
- FIG. 7 is a perspective view illustrating a support portion of the sensor-mounted helmet of the magnetoencephalography measuring apparatus.
- FIG. 8 is a view when viewed from a lower surface of the internal container of the magnetoencephalography measuring apparatus.
- FIG. 9 is a perspective view illustrating a sensor-mounted helmet according to an example embodiment of the present disclosure.
- FIG. 10 is a cross-sectional view of the sensor-mounted helmet of FIG. 9 .
- FIG. 11 is a conceptual diagram illustrating a connection relationship between a main thermal anchor and a SQUID sensor module according to an example embodiment of the present disclosure.
- FIG. 12 is a cross-sectional view of the main thermal anchor.
- FIG. 13A is a perspective view illustrating a SQUID sensor module according to an example embodiment of the present disclosure.
- FIG. 13B is an exploded perspective view illustrating the SQUID sensor module of FIG. 13A .
- FIG. 13C is a cross-sectional view illustrating a SQUID sensor module according to an example embodiment of the present disclosure.
- FIG. 14 is a perspective view illustrating a SQUID sensor module according to another example embodiment of the present disclosure.
- a technology for directly recondensing a helium gas using a refrigerator and resending the recondensed helium gas to a Dewar is applied. Since magnetic noise and vibration noise caused by the refrigerator and refrigerant delivery tube are significantly large, a special Dewar structure and a special SQUID arrangement method are required to prevent a SQUID from reacting with vibrations. In particular, a stable structure for supporting a SQUID-mounted helmet is required.
- Vaporized helium is supplied to a refrigerator through a refrigerant exhaust tube, and a liquefied refrigerant is supplied to a Dewar through a refrigerant injection tube.
- the refrigerant exhaust tube and the refrigerant injection tube include a single pipe, ice is condensed on a baffle insert lid. Such ice inhibits perfect sealing to causes lots of external heat influx.
- a CIV SQUID addresses an issue regarding ice condensation on a baffle insert lid using a coaxial dual-tube structure.
- a refrigerant exhaust tube and a refrigerant injection tube have a coaxial structure, and each of the refrigerant exhaust tube and the refrigerant injection tube has a dual-tube structure.
- the dual-tube structure may prevent moisture condensation occurring on a surface of an upper plate of a Dewar. Accordingly, rotation of the Dewar may be provided using a sealing member such as an O-ring.
- the dual-tube structure may transfer a temperature of an evaporated helium gas to a cooler in a cold state, and thus, efficiency of the cooler may be improved.
- the Dewar includes an internal container and an external container surrounding the internal container.
- the internal container absorbs radiant heat externally to increase consumption of a refrigerant.
- the Dewar uses a double-wall structure in a neck portion of the internal container into which a baffle insert is inserted.
- a double-wall structure improves mechanical stability resulting from thermal expansion.
- a heat shielding layer disposed between the double walls reduces influx of radiant heat.
- a thermal anchor disposed on the outside of the double-wall structure uses a screw coupling to reduce damage caused by thermal expansion while being in thermal contact with an internal wall of the internal container having a double-wall structure through a large contact area.
- the double-wall structure may reduce an evaporation rate of the refrigerant and may stably support an internal structure with a high load, allowing internal vibration caused by evaporation of the refrigerant to be reduced.
- a magnetoencephalography (MEG) signal depends on a distance between a SQUID sensor and a brain. Therefore, an MEG helmet for adults is not suitable to measure MEG of children. Accordingly, there is a need for a dual helmet in which a single MEG apparatus can measure both adults and children.
- a helmet for children may be provided with 144 channels, and a helmet for adults may be provided with 192 channels. Therefore, as a structure optimal for a head size, it is expected that the quality of, in particular, children's MEG signals will be improved. It is advantageous to measure development processes of children's brain functions to adults' brain functions.
- a magnetoencephalography apparatus has a structure in which two helmets are disposed on a single Dewar. A helmet for children and a helmet for adults, having different sizes, are mounted to face each other.
- each of a helmet for children and a helmet for adults may measure magnetoencephalography in a lying state according to a rotation state of a Dewar.
- a rotational motion unit may provide a rotation motion of the Dewar using a non-metallic bearing.
- the rotational motion unit may include a signal line connection box, to which signal lines are connected, therein.
- a magnetoencephalography apparatus includes a main thermal anchor disposed on a lower surface of an internal container.
- the main thermal anchor includes a plurality of heat transfer portions, screw-coupled to each other, and a thermal expansion control portion formed of an insulating material and controlling sealing failure caused by thermal expansion between the heat transfer portion and the internal container.
- a pair of thermal expansion control portions disposed to be embedded in an external surface and an internal surface of the internal container, are pressed to inhibit damage to components caused by sealing and thermal expansion.
- FIG. 1 is a conceptual diagram illustrating a magnetoencephalography measuring apparatus according to an example embodiment of the present disclosure.
- FIG. 2 is a perspective view illustrating a magnetoencephalography measuring apparatus.
- FIG. 3 is a cross-sectional view taken along line A-A′ in FIG. 2 .
- FIG. 4 is a perspective view illustrating an internal container and a sensor-mounted helmet.
- FIG. 5 is an exploded perspective view illustrating a rotational motion unit supporting an external container and providing a rotational motion.
- FIG. 6 is an enlarged cross-sectional view of the internal container of the magnetoencephalography measuring apparatus.
- a magnetoencephalography measuring apparatus 300 includes an internal container 360 storing a liquid refrigerant, an external container 310 disposed to surround the internal container 360 and including a first external helmet 320 and a second external helmet 330 disposed to be spaced apart from each other, a first sensor-mounted helmet 322 disposed to surround the first external helmet 320 between the external container 310 and the internal container 360 , a second sensor-mounted helmet 332 disposed to surround the second external helmet 330 between the externa container 310 and the internal container 360 , a plurality of first SQUID sensor module 103 a disposed on the first sensor-mounted helmet 322 , and a plurality of second SQUID sensor module 103 b disposed on the second sensor-mounted helmet 332 .
- a space between the external container 310 and the internal container 360 is in a vacuum state.
- Each of the plurality of first SQUID sensor modules 103 a is in thermal contact with a main thermal anchor 170 disposed on a lower surface of the internal container 360 through a litz wire 12 .
- Each of the plurality of second SQUID sensor modules 103 b is in thermal contact with the main thermal anchor 170 disposed on the lower surface of the internal container 360 through the litz wire 12 .
- the space between the external container 310 and the internal container 360 is in a vacuum state.
- the SQUID sensor of the first helmet-mounted sensor 322 and the second helmet-mounted sensor 332 may be efficiently cooled through the litz wire 12 .
- the magnetoencephalography measuring apparatus 300 may be disposed inside a magnetically shielded room 11 .
- the external container 310 may branch off in the form of T.
- the external container 310 may include a first branch 312 and a second branch 314 branching off from a cylindrical external container body portion 316 in the form of T.
- Each of the first external helmet 320 and the second external helmet 330 may be coupled to the first branch 312 and the second branch 314 , respectively.
- the first external helmet 320 and the second external helmet 330 may face each other and may have different sizes.
- a diameter of each of the first branch 312 and the second branch 314 may be greater than a diameter of the external container body portion 316 .
- the first external helmet 320 may include an open portion 321 for securing a view.
- the external container body portion 316 may be vertically disposed, and the first branch 312 and the second branch 314 may be horizontally disposed.
- the external container 310 may be a glass fiber reinforced plastic such as G10 epoxy.
- the external container body portion 316 may have a cylindrical shape and may rotate about a central axis thereof.
- the first external helmet 320 or the first external helmet 320 may measure a magnetoencephalography signal for children or adults according to a rotation state of the external container 310 .
- a rotational motion unit 340 may be coupled to lower surfaces of the first branch 312 and the second branch 314 .
- the rotational motion unit 340 may include a bearing formed of a non-conductive material.
- the rotational motion unit 340 may be mounted on a bottom of the magnetically shielded room 11 .
- the first external helmet 320 may be provided with a long groove 320 a in a portion coupled to the first branch 312 .
- the first external helmet 320 may rotate along the long groove 320 a to be coupled to one end of the first branch 312 in a state of being aligned therewith.
- the long groove 320 a may provide alignment between the first external helmet 320 and the first sensor-mounted helmet 322 .
- the first external helmet 320 may include the open portion 321 for securing a view.
- the second external helmet 330 may be provided with a long groove in a portion coupled to the second branch 314 .
- the second external helmet 330 may rotate along the long groove to be coupled to one end of the second branch 314 in a state of being aligned therewith.
- the internal container 360 may store a liquid refrigerant, and may cool the SQUID sensor modules 103 a and 103 b through the main thermal anchor 170 and the litz wire 12 .
- a material of the internal container 360 may be a glass fiber reinforced plastic such as G10 epoxy.
- the internal container 360 may include a neck portion 362 into which a baffle insert 150 is inserted, a first body portion 364 having an increased diameter as compared with the neck portion 362 , a second body portion 366 having an increased diameter as compared with the first body portion 364 ; and a third body portion 368 having a decreased diameter as compared with the second body portion.
- the internal container 360 may include a body portion and a neck portion 362 into which the baffle insert 150 is inserted.
- the body portion may include a first body portion 364 having an increased diameter as compared with the neck portion 362 , a second body portion 366 having an increased diameter as compared with the first body portion, and a third body portion 368 having a decreased diameter as compared with the second body portion.
- the neck portion 362 may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- the first body portion 364 may be continuously connected to the neck portion 362 .
- the second body portion 366 may be continuously connected to the first body portion 364 .
- the second body portion 366 may have a greater diameter than the first body portion 364 .
- the third body portion 368 may be continuously connected to the second body portion 366 .
- the third body portion 368 may have a smaller diameter than the second body portion 366 .
- the first body portion 364 and the third body portion 368 may have the same diameter.
- the first sensor-mounted helmet 322 and the second sensor-mounted helmet 332 are arranged symmetrically with respect to the first to third body portions 364 , 366 , and 368 to provide mechanical stability and symmetry of cooling.
- a lower surface 368 a of the third body portion 368 may include a plurality of getter grooves 368 b having a fan shape in a direction toward a lower surface or a vacuum side.
- a getter, collecting residual gas in a vacuum state, may be disposed in the getter groove 368 b.
- the neck portion 362 may include an internal cylinder 162 a and an external cylinder 162 b surrounding the internal cylinder 162 a.
- the heat shielding film 162 c may be disposed between the internal cylinder 162 a and the external cylinder 162 b.
- the heat shielding layer 162 c may have a multilayer structure in which a metal thin film, having high reflectivity and low emissivity, and a significantly thin nonwoven fabric, having low thermal conductivity, are sequentially stacked.
- the internal cylinder 162 a may further include a plurality of ring projections 162 a ′ protruding outwardly of a cylinder.
- the ring projection 162 a ′ may have a cylindrical ring shape, and may be formed to be integrated with the internal cylinder 162 a.
- a screw for screw-coupling may be formed on an external circumferential surface of the ring projection 162 a′.
- the ring projections 162 a ′ may be disposed to be spaced apart from each other.
- the external cylinder 162 b may be separated with the ring projection 162 a ′ interposed therebetween. That is, the external cylinder 162 b may include a plurality of cylindrical components separated from each other. A distance between the external cylinder 162 b and the internal cylinder 162 a may be within several millimeters (mm).
- Each of the external cylinders 162 a may have a raised spot to surround a thermal anchor coupling portion 106 a ′′ and the ring projection 162 a ′.
- the external cylinder 162 b may be coupled to surround the ring projection 162 a ′, a coupling portion may be fixed and sealed with an adhesive such as epoxy.
- the thermal anchors 106 a, 106 b, and 106 c may be coupled to the ring projections 162 a ′, respectively.
- An external circumferential surface of the ring projection 162 a ′ and the internal circumferential surface of the thermal anchors 106 a, 106 b, 106 c may be screw-coupled to each other.
- Each of the thermal anchors 106 a, 106 b, and 106 c may have a circular washer shape.
- Each of the thermal anchors 106 a, 106 b, and 106 c may include copper (Cu) or aluminum (Al).
- the thermal anchor 106 a may include a cylindrical thermal anchor coupling portion 106 a ′′ and a disc-shaped thermal anchor body portion 106 a ′ disposed on an external circumferential surface of the coupling portion.
- An internal circumferential surface of the thermal anchor coupling portion 106 a ′′ may be screw-coupled to the external circumferential surface of the ring projection 162 a ′. Accordingly, the thermal anchors 106 a, 106 b, and 106 c may be stably fixed to the internal container and may be cooled while being in thermal contact with each other through a wide area.
- the screw-coupling of the ring projection 162 a ′ and the thermal anchor 106 a may improve mechanical stability while providing efficient thermal contact caused by thermal expansion.
- the double-wall structure may prevent radiant heat from flowing into the internal container 360 from an external entity.
- a space between the internal cylinder and the external cylinder may be maintained in a vacuum state. Accordingly, heat influx caused by heat transfer may be blocked, and the heat shielding layer 162 c may additionally block the influx of the radiant heat. Accordingly, a neck portion of the double-wall structure may provide high mechanical stability and high heat shielding efficiency, as compared with to a neck portion of a single-wall structure.
- the thermal anchors 106 a, 106 b, and 106 c may include first to third thermal anchors 106 a, 106 b, and 106 c disposed in order.
- the first thermal anchor 106 a may be disposed on an uppermost side of the neck portion 362 , and may be connected to a 120K heat shielding layer 107 a.
- the second thermal anchor 106 b may be disposed under the first thermal anchor 106 a and connected to an 80K heat shielding layer 107 b.
- the third thermal anchor 106 c may be disposed on a lower side of the second thermal anchor 106 b, and may be connected to a 40K heat shielding layer 107 c.
- An external diameter of the first thermal anchor 106 a may be greater than an external diameter of the second thermal anchor 106 b.
- the first thermal anchor 106 a may be spaced farthest apart from the refrigerant to be maintained at a highest temperature, and the third thermal anchor 106 c may be closest to the refrigerant to be maintained at a lowest temperature.
- the first to third thermal anchors 106 a , 106 b, and 106 c may be in thermal contact with an evaporated refrigerant to be cooled.
- the 40K heat shielding layer 107 c may be coupled to an external circumferential surface of the third thermal anchor 106 c, and may be disposed to surround the internal container 360 to block the influx of radiant heat.
- the 40K heat shielding layer 107 c may include a heat insulating layer a metal mesh woven with metal wires insulated from each other.
- the 40K heat shielding layer 107 c may branch off in the form of T to surround the first sensor-mounted helmet 322 and the second sensor-mounted helmet 332 , and then may surround the first sensor-mounted helmet 322 and the second sensor-mounted helmet 133 .
- the 80K heat shielding layer 107 b may be coupled to an external circumferential surface of the second heat anchor 106 b, and may be disposed to surround the 40K heat shielding layer 107 c and to block the influx of radiant heat.
- the 80K heat shielding layer 107 b may include a heat insulating layer and a metal mesh woven with metal wires insulated from each other.
- the 80K heat shield 107 b may branch into in the form of T to surround the first sensor-mounted helmet 322 and the second sensor-mounted helmet 332 .
- the 80K heat shield 107 b may extend in a direction of a brim of the first sensor-mounted helmet 322 , and may extend in a direction of a brim of the second sensor-mounted helmet 332 .
- the 120K heat shielding layer 107 a may be coupled to an external circumferential surface of the first heat anchor 106 a, and may be disposed to surround the 80K heat shielding layer 107 b and to block the influx of radiant heat.
- the 120K heat shielding layer 107 a may include a heat insulating layer and a metal mesh woven with metal wires insulated from each other.
- the 120K heat shielding layer 107 a may branch off in the form of T to surround the first sensor-mounted helmet 322 and the second sensor-mounted helmet 332 .
- Each of the heat shielding layers 107 a, 107 b, and 107 c may have an opening in a direction toward the external container support portion 341 .
- the openings may be disposed so as not to overlap each other. Accordingly, signal lines may pass through the openings of the heat shielding layer 107 a, 107 b, and 107 c in a zigzag shape to pass through a vacuum sealing portion 344 .
- the space between the internal container 360 and the external container 310 may be maintained in a vacuum state.
- the external container lid 311 may include an exhaust port 311 a connected to a vacuum pump.
- the exhaust port 311 a may be formed of a G-10 epoxy tube.
- the baffle insert 150 may be disposed to be inserted into the neck portion 362 of the internal container 360 .
- the baffle insert 150 may include an insert upper plate 151 , a baffle 156 disposed below the insert upper plate, and a plurality of guide rods 154 supporting the baffle 156 and fixed to the insert upper plate 151 .
- the insert upper plate 151 may have a disc shape and may be formed of G-10 epoxy.
- the insert upper plate 151 may be fixed to the external container lid 311 .
- the guide rod 154 is formed of G-10 epoxy, and may have a rod shape or a pipe shape.
- the guide rod 154 may support the baffle 156 .
- the baffle 156 may include Styrofoam having improved warmth retention and a conductive plate.
- the conductive plate may include an aluminum-coated Mylar layer and a copper layer sequentially stacked to block the radiant heat.
- a refrigerant exhaust tube 153 may be disposed on the insert upper plate of the baffle insert 150 , and may exhaust the evaporated refrigerant.
- the refrigerant injection tube 152 may be disposed on the insert upper plate 151 of the baffle insert 150 , and may inject a refrigerant.
- Each of the refrigerant exhaust tube 153 and the refrigerant injection tube 152 may be a dual tube including an internal tube and an external tube. In the dual tube, a space between the internal tube and the external tube may be maintained in a vacuum state during cooling.
- the refrigerant injection tube 152 may have a coaxial structure inserted into the refrigerant exhaust tube 153 .
- the refrigerant exhaust tube 153 and the refrigerant injection tube 152 may be formed of G-10 epoxy.
- Coaxial dual tubes 152 and 153 may reduce thermal contact with the insert upper plate 151 to reduce ice formation of the insert upper plate 151 .
- the insert upper plate 151 and the refrigerant exhaust tube may form ice to impede sealing of the external container lid 111 and the insert upper plate 151 and to increase influx of external heat.
- the coaxial dual tubes 152 and 153 may be disposed on a central axis of the insert upper plate 151 .
- One end of the refrigerant exhaust tube 153 may be disposed in a higher location than the first heat anchor 106 a.
- the coaxial dual tubes 152 and 153 may not rotate while maintaining the sealing using a sealing means such as an O-ring.
- the condenser 159 may be connected to the refrigerant exhaust tube 153 and the refrigerant injection tube 152 , and may condense the vaporized refrigerant exhausted through the refrigerant injection tube 153 .
- the condenser 159 may be disposed outside the magnetically shielded room 11 .
- the rotational motion unit 340 may be coupled to lower surfaces of the first branch 312 and the second branch 314 .
- the rotational motion unit 340 may provide a rotational motion of the external container 310 .
- the rotational motion unit 340 may include an external container support portion 341 , an upper support box 342 , a lower support box 347 , and a bearing portion 346 .
- the external container support portion 341 may be in the form of C, and may support the lower surfaces of the first branch 312 and the second branch 314 .
- the external container support portion 341 may have a through-hole in a center thereof.
- a vacuum sealing portion 344 may be inserted into through-holes formed in the lower surface of the first branch 312 and the second branch 314 to seal signal lines, and be disposed inside the external container support portion 341 .
- the vacuum sealing portion 344 may seal the external container 310 in a vacuum state and the outside in an atmospheric pressure state to each other.
- a signal line connection box 345 may be disposed below the external container support portion 341 , and may connect the sealed signal lines 15 to each other through the vacuum sealing portion 344 .
- the signal line connection box 345 may be disposed inside the upper support box 342 .
- the upper support box 342 may be disposed to surround the signal line connection box 345 , and may have a cylindrical shape.
- the upper support box 342 may support the external container support portion 341 .
- a handle 343 may be coupled to an external side of the upper support box 342 .
- a user may rotate the handle 343 to select a rotational state of a magnetoencephalography measuring apparatus.
- the lower support box 347 may be disposed below the upper support box 342 .
- the bearing portion 346 may be disposed between the upper support box 342 and the lower support box 347 to provide a rotational motion of the upper support box 342 .
- FIG. 7 is a perspective view illustrating a support portion of the sensor-mounted helmet of the magnetoencephalography measuring apparatus.
- FIG. 8 is a view when viewed from a lower surface of the internal container of the magnetoencephalography measuring apparatus.
- FIG. 9 is a perspective view illustrating a sensor-mounted helmet according to an example embodiment of the present disclosure.
- FIG. 10 is a cross-sectional view of the sensor-mounted helmet of FIG. 9 .
- a first sensor-mounted helmet 322 may be configured to cover a head, and may include an open portion to secure a subject's view.
- the first sensor-mounted helmet 322 may include brims 322 a ′ and 322 a ′′ on edges thereof.
- the brim 322 a ′ and 322 a ′′ may be connected to a fixing means for fixing the first sensor-mounted helmet 322 .
- a second sensor-mounted helmet 332 may be configured to cover a head, and includes an open portion to secure a subject's view.
- the second sensor-mounted helmet 332 may include a brim on an edge thereof.
- the brim may be connected to a fixing means for fixing the second sensor-mounted helmet 332 .
- a pair of first support portions 382 may be coupled to an interface between the neck portion 362 and the first body portion 364 , and may extend in a direction of the first external helmet 320 and in a direction of the second external helmet 330 , respectively.
- the first support portion 382 may include a C-shaped portion 382 c, coupled to the interface between the neck portion 362 and the first body portion 364 , and a pair of pillars 382 b extending parallel to a direction of a corresponding external helmet.
- the C-shaped portion 382 c may have a plurality of arc-shaped long grooves 382 a.
- a fixing means may be coupled to each of the arc-shaped long grooves 382 a to provide alignment with a corresponding sensor-mounted helmet.
- a pair of second support portions 384 may be coupled to an interface between the first body portion 364 and the second body portion 366 , and extend in the direction of the first external helmet 320 and in the direction of the second external helmet 330 , respectively.
- the second support portion 384 may include a C-shaped portion, coupled to an interface between the first body portion 364 and the second body portion 366 , and a pair of pillars extending parallel to a direction of a corresponding external helmet.
- the C-shaped portion may include a plurality of arc-shaped long grooves 384 a.
- a fixing means may be coupled to each of the arc-shaped long grooves 384 a to provide alignment with a corresponding sensor-mounted helmet.
- a pair of third support portions 386 may be coupled to an interface between the second body portion 386 and the third body portion 388 , and may extend in a direction of the first external helmet 320 and in a direction of the second external helmet 330 , respectively.
- the second support portion 384 may include a C-shaped portion, coupled to an interface between the second body portion 386 and the third body portion 388 , and a pair of pillars extending parallel to a direction of a corresponding external helmet.
- the C-shaped portion may include a plurality of arc-shaped long grooves 386 a.
- a fixing means may be coupled to the arc-shaped long groove to provide alignment with a corresponding sensor-mounted helmet.
- a first fixing ring 387 may be coupled to the first support portion 382 , the second support portion 384 , and the third support portion 386 in a direction of the first external helmet 320 .
- a second fixing ring 388 may be coupled to the first support portion 382 , the second support portion 384 , and the third support portion 386 in a direction of the second external helmet 330 .
- a first auxiliary fixing part 323 may connect the first fixing ring 387 and the first sensor-mounted helmet 322 to each other.
- the first auxiliary fixing part 323 may include an upper ring 323 a, a lower ring 323 c spaced apart from the upper ring 323 a, and a plurality of support rods 323 b connecting the upper ring 323 a and the lower ring 323 c to each other.
- the second auxiliary fixing part 333 may connect the second fixing ring 388 and the second sensor-mounted helmet 332 to each other.
- the second auxiliary fixing part 333 may include an upper ring, a lower ring spaced apart from the upper ring, and a plurality of support rods connecting the upper ring and the lower ring to each other.
- the first sensor-mounted helmet 322 may include brims 322 a ′ and 322 a ′′ on edges thereof.
- the first sensor-mounted helmet 322 may have the same structure as the second sensor-mounted helmet 332 , but the first sensor-mounted helmet 322 may be different, in size and the number of SQUID sensor modules, from the second sensor-mounted helmet 332 .
- the first sensor-mounted helmet 322 may have a first through-hole 322 b for mounting a SQUID sensor module, a second through-hole 322 c for placing a signal line, and a third through-hole for mounting a fixing member for fixing the SQUID sensor module 103 a.
- the first sensor-mounted helmet 322 may include a helmet body 322 ′ having an open region for securing a view, a lower brim 322 a ′ disposed along an edge of a lower surface of the helmet body, an upper brim 322 a ′′ providing a brim in the open portion of the helmet body, a helmet fixing ring 322 f having a ring shape at a predetermined interval from the lower brim 322 a ′ and continuously connected to the upper brim 322 a ′′, and a plurality of connection pillars 322 e vertically connecting the lower brim 322 a ′ and the upper brim 322 a ′′ to each other.
- the brim of the first sensor-mounted helmet 322 may include an upper brim, disposed in an open portion to secure a view, and a lower brim surrounding a subject's occipital region.
- the first auxiliary thermal anchor 185 may be disposed on a lower surface of the brim 322 a of the first sensor-mounted helmet 322 .
- the first auxiliary thermal anchor 185 may be divided into a plurality of components 185 a to 185 d.
- the first auxiliary thermal anchor 185 may be fabricated using an oxygen-free copper strip.
- the divided first auxiliary thermal anchor 185 may be divided into four pieces to reduce eddy current noise, caused by high-frequency magnetic noise, and thermal noise, caused by free electrons of a metal, and may provide a uniform location-dependent temperature gradient.
- the first auxiliary thermal anchor 185 may be in thermal contact with the main thermal anchor 170 by a litz wire 12 .
- a first internal 4K heat shielding portion 124 may be in thermal contact with the first auxiliary thermal anchor 185 , and may be disposed on an internal side surface of the first sensor-mounted helmet 322 .
- the first internal 4K heat shielding portion 124 may be disposed to surround the SQUID sensor modules 103 a, and may include an insulation-coated metal mesh.
- a first external 4K heat shielding portion 126 may be in thermal contact with the first auxiliary thermal anchor 185 , and may be disposed on an external side surface of the first sensor-mounted helmet 322 .
- the first external 4K heat shielding portion 126 may be disposed to surround an external side surface of the first sensor-mounted helmet 322 .
- the first external 4K heat shielding portion 126 may include an insulation-coated metal mesh. Accordingly, the first auxiliary heat anchor 185 , the first internal 4K heat shielding portion 124 , and the first external 4K heat shielding portion 126 may be in thermal contact with the main heat anchor 170 by a litz wire 12 .
- a second auxiliary thermal anchor may be disposed on a lower surface of the brim of the second sensor-mounted helmet 332 .
- a second internal 4K heat shielding portion may be in thermal contact with the second auxiliary thermal anchor, and may be disposed on an internal side surface of the second sensor-mounted helmet 332 .
- the second external 4K heat shielding portion may be in thermal contact with the second auxiliary thermal anchor, and may be disposed on an external side surface of the second sensor-mounted helmet.
- the second auxiliary heat anchor, the second internal 4K heat shielding portion, and the second external 4K heat shielding portion may be in thermal contact with the main heat anchor 170 through a litz wire 12 .
- FIG. 11 is a conceptual diagram illustrating a connection relationship between a main thermal anchor and a SQUID sensor module according to an example embodiment of the present disclosure.
- FIG. 12 is a cross-sectional view of the main thermal anchor.
- each of the plurality of first SQUID sensor modules 103 a may be in thermal contact with a main thermal anchor 170 disposed on the lower surface of the internal container 360 through a litz wire 12 .
- Each of the plurality of second SQUID sensor modules 103 b may be in thermal contact with the main thermal anchor 170 disposed on the lower surface of the internal container 360 through the litz wire 12 .
- the main heat anchor 170 may include a first heat transfer unit 171 , a second heat transfer unit 172 , a third heat transfer unit 173 , a fourth heat transfer unit 174 , a fifth heat transfer unit 175 , a first thermal expansion control unit 176 , and a second thermal expansion control unit 177 .
- the main thermal anchor 170 may include of a plurality of components to increases a thermal contact area while inhibiting damage to the internal container caused by thermal expansion, and thus, may efficiently cool a litz wire 12 and a SQUID sensor.
- the first thermal expansion control unit 176 may be coupled to a double groove having two radii formed on an internal side of the lower surface of the internal container, and the second thermal expansion control unit 177 may be coupled to a double groove having two radii formed on an external side of the lower surface of the internal container.
- the first heat transfer unit 171 may be formed of oxygen-free copper, and may include a first disc 171 a and a first lower projection 171 b protruding from a central axis of the first disc 171 a to a lower surface of the first disc 171 a.
- the first heat transfer unit 171 may further include a first upper projection 171 c protruding from the central axis of the first disc 171 a to an upper surface of the first disc 171 a.
- the second heat transfer unit 172 may be formed of oxygen-free copper, and may include a second disc 172 a, a second upper projection 172 b protruding from a central axis of the second disc 172 a to an upper surface of the second disc 172 a, and a second lower projection 172 c protruding from the central axis of the second disc 172 a to a lower surface of the second disc 172 a.
- the second upper projection 172 b of the second heat transfer unit 172 may include a screw groove 172 d for coupling to the first lower projection 171 b of the first heat transfer unit 171 .
- the second lower projection 172 c of the second heat transfer unit 172 may have a screw groove 172 e for coupling to the third upper projection 173 b of the third heat transfer unit 173 .
- the third heat transfer unit 173 may be formed of oxygen-free copper, and may include a third disc 173 a, a third upper projection 173 b protruding from a central axis of the third disc 173 a to an upper surface of the third disc 173 a, and a third lower projection 173 c protruding from the central axis of the third disc 173 a to a lower surface of the third disc 173 a.
- the third lower projection 173 c of the third heat transfer unit 173 may have a screw groove 173 d for coupling to the fourth upper projection 174 b of the fourth heat transfer unit 174 .
- the fourth heat transfer unit 174 may be formed of oxygen-free copper, and may include a fourth disc, a fourth upper projection 174 b protruding from a central axis of the fourth disc to an upper surface of the fourth disc, and a fourth lower projection 174 c protruding from the central axis of the fourth disc to a lower surface of the fourth disc.
- the fifth heat transfer unit 175 may be formed of oxygen-free copper, and may include a C-shaped plate.
- the fifth heat transfer unit 175 may be coupled to the fourth lower projection 174 c of the fourth heat transfer portion 174 .
- a lower surface of the fifth heat transfer unit 175 may be coupled to a fixing means 178 .
- the fixing means 178 may fix and cool the litz wire 12 connected to the SQUID sensor module 103 a.
- the first thermal expansion control unit 176 may be formed of an insulating material, or and may be inserted between the first disc 171 a of the first heat transfer unit 171 and the second disc 172 b of the second heat transfer unit 172 .
- the first thermal expansion control unit 176 may include the same material as the internal container.
- the second thermal expansion control unit 177 may be formed of an insulating material, and may be inserted between the third disc 173 a of the third heat transfer unit 173 and the fourth disc 174 a of the fourth heat transfer unit 174 .
- the second thermal expansion control unit 177 may include the same material as the internal container.
- the first thermal expansion control unit 176 may include a first insulating body portion 176 a having the same diameter as a first diameter D 1 of the first disc 171 a, a second insulating body portion 176 b embedded in a lower surface of the internal body and having a second diameter D 2 greater than the first diameter D 1 , and a third insulating body portion 176 c having a third diameter D 3 smaller than the second diameter D 2 .
- the third insulating body portion 176 c may be disposed to surround an external circumferential surface of the second disc 172 a.
- An external circumferential surface of the third insulating body portion 176 c may be provided with a screw groove.
- the second thermal expansion control unit 177 may have the same structure as the first thermal expansion control unit 176 .
- the first thermal expansion control unit 176 and the second thermal expansion control unit 177 may be pressed to be sealed with the internal container.
- the first disc 171 a and the fourth disc 174 a may be sealed by pressing the first thermal expansion control unit 176 and the second thermal expansion control unit 177 .
- the main thermal anchor 170 may cool the first SQUID sensor module 103 a and the second SQUID sensor module 103 b through a litz wire.
- Each of the first SQUID sensor modules 103 a may be cooled by a plurality of litz wires 12 . Some of the plurality of Litz wires 12 may be provided to a neighboring first SQUID sensor module 103 a. The remainder of the plurality of litz wires 12 may be in thermal contact with the main thermal anchor 170 .
- Each of the first SQUID sensor modules 130 a may be cooled by six litz wires 12 .
- Two litz wires 12 may be in thermal contact with the main thermal anchor 170 , and the rest four litz wires 12 may be connected to a neighboring first SQUID sensor module 103 a.
- Each of the first SQUID sensor modules 103 a may be inserted into a through-hole, formed in the first sensor mounting helmet 322 , to be fixed.
- the first SQUID sensor module 103 a may have a plurality of holes 611 .
- the litz wire 12 may be inserted into the holes 611 to cool the SQUID sensor 646 .
- FIG. 13A is a perspective view illustrating a SQUID sensor module according to an example embodiment of the present disclosure.
- FIG. 13B is an exploded perspective view illustrating the SQUID sensor module of FIG. 13A .
- FIG. 13C is a cross-sectional view illustrating a SQUID sensor module according to an example embodiment of the present disclosure.
- a SQUID sensor module 103 a / 103 b may include a fixed block 610 having one end fixed to a sensor-mounted helmet 122 / 132 , a bobbin 630 having one end coupled to the other end of the fixed block 610 and provided with a groove around which a pick-up coil 601 is wound, a bobbin fixing means 650 fixed to the other end of the fixed block 610 through a through-hole formed in a center of the bobbin 630 , a superconducting quantum interference device (SQUID) printed circuit board (PCB) 640 disposed on an upper side surface of the bobbin 630 and including a SQUID sensor 646 , and a signal line connection PCB 620 inserted into an external circumferential surface of the fixed block 610 and transferring a signal, detected by the SQUID sensor 646 , to an external circuit.
- SQUID superconducting quantum interference device
- the sensor-mounted helmets 122 and 132 may mount a SQUID sensor module 600 , and may be disposed in a vacuum space between an external container and an internal container.
- the sensor-mounted helmets 122 and 132 may be formed of a non-magnetic material.
- the sensor-mounted helmets 122 and 132 may include a first sensor-mounted helmet 322 and a second sensor-mounted helmet 332 mounting a SQUID sensor module.
- the fixed block 610 may be formed of a non-magnetic material, such as G10 epoxy, in an integral type.
- the fixed block 610 may be inserted into the through-hole 122 b formed in the sensor-mounted helmet to be fixed through an adhesive.
- the fixed block 610 may include a fixed block projection 612 , a fixed block threshold portion 614 , a fixed block body portion 616 , and a fixed block extending portion 618 .
- the fixed block 610 may have a plurality of holes 611 in a central axis direction in which a litz wire for cooling is inserted.
- the litz wire may be inserted into each of a plurality of holes 611 to cool the SQUID sensor 646 .
- the fixed block projection 612 may have a disc shape, and may be coupled to a groove or a through-hole 122 b formed in the sensor-mounted helmet. In addition, the fixed block projection 612 may be fixed to the through-hole through an adhesive.
- the fixed block threshold portion 614 may have a disc shape and may be continuously connected to the fixed block projection portion 612 .
- the fixed block threshold portion 614 may have a greater diameter than the fixed block projection 612 .
- the fixed block threshold portion 614 may have a planar side surface 614 a.
- One side surface 614 a of the fixed block threshold 614 may be a plane having a predetermined first vertical distance from a central axis having a cylindrical shape.
- the fixed block threshold portion 614 may serve to perform an alignment in a central axis direction.
- a through-hole 619 may be formed in an exterior of the fixed block threshold 614 .
- the fixed block body portion 616 may be a portion coupled to the signal line connection PCB 620 .
- the signal line connection PCB 620 may be disposed to be inserted into the external peripheral surface of the fixed block body portion 616 .
- the signal line connection PCB 620 may include a hole 623 on an external periphery thereof.
- the through-hole 619 of the fixed block threshold 614 may be aligned with the hole 623 of the signal line connection PCB 620 .
- the fixing means may be inserted into the through-hole 619 of the fixed block threshold portion 614 and the hole 623 of the signal line connection PCB 620 to fix the fixed block threshold portion 614 and the signal line connection PCB 620 to each other.
- An internal diameter of the signal line connection PCB 620 may be substantially the same as an external diameter of the fixed block body portion 616 .
- the external diameter of the signal line connection PCB 620 may be substantially the same as an external diameter of the fixed block threshold 614 .
- the signal line connection PCB 620 has a washer shape having a central through-hole therein. When the signal line connection PCB 620 is coupled to the external circumferential surface of the fixed block 610 , one side of the central through-hole may be planar so as to inhibit a rotational motion.
- the signal line connection PCB 620 may include a first connector 622 .
- the first connector 622 may be a female connector.
- the first connector 622 may be disposed on an edge of a lower surface of the signal line connection PCB 620 .
- a connection terminal 624 and a wiring may be disposed on an upper surface of the signal line connection PCB 620 .
- the connection terminal 624 may be connected to the first connector 622 through the wiring.
- a connection wire, connected to an external circuit may be coupled to the connection terminal 624 .
- the fixed block body portion 616 may have a disc shape and may be continuously connected to the fixed block threshold portion 614 .
- the fixed block body portion 616 may have a smaller diameter than the fixed block threshold portion 614 , and may have a planar side surface 616 a.
- One side surface 616 a of the fixed block body portion 616 may be a plane having a predetermined second vertical distance from the central axis having a cylindrical shape.
- the fixed block extending portion 618 may have the same diameter as the fixed block body portion 616 , and may have a planar side surface 618 a.
- the side surface 618 a may be a plane having a predetermined third vertical distance from the central axis having a cylindrical shape. The third vertical distance may be smaller than the second vertical distance.
- One planar side surface 614 a of the fixed block threshold portion 614 and one planar side surface 616 a of the fixed block body portion 616 may be connected to each other.
- the one side surface 616 a of the fixed block body 616 and the one side surface 618 a of the fixed block extending portion 618 may be spaced apart from each other to be parallel to each other.
- a vertical distance between a central axis and one side surface of the fixed block extending portion 618 may be smaller than a vertical distance between the central axis and one side surface of the fixed block body portion 616 .
- the bobbin 630 may be formed of a non-magnetic material such as G10 epoxy.
- the bobbin 630 may have a cylindrical shape.
- the bobbin 630 includes a first planar portion 634 , formed on an upper side surface having a first vertical distance from the central axis, and a second planar portion 634 formed on a lower side surface 636 having a second vertical distance larger than the first vertical distance.
- the bobbin 630 may have a groove 632 formed around a lower side surface thereof. The groove may form a closed loop.
- a pick-up coil 601 may be wound around the groove 632 .
- a hole 635 may be formed in the first planar portion 634 .
- the hole 635 may be coupled to a fixing means for fixing the SQUID PCB 640 .
- the SQUID PCB 640 may be disposed on the first planar portion 634 . Both ends of the pick-up coil 601 may be fixed to the second planar portion 636 through an adhesive.
- the pick-up coil 601 may be electrically connected to the SQUID sensor 646 through a connection line 648 formed of a superconductor material.
- the connection line 648 may include a niobium (Nb) material.
- the SQUID PCB 640 may include a second connector 642 and a SQUID sensor 646 and disposed on a PCB substrate 644 .
- the SQUID sensor 646 may be in the form of a semiconductor chip.
- the SQUID sensor 646 may include an input coil and a Josephson junction.
- the SQUID sensor 646 may include a conductive pad for electrical connection to the pick-up coil 601 .
- the conductive pad may connect the pick-up coil 601 .
- the second connector 642 may be electrically connected to another conductive pad.
- the second connector 642 may be a pin-type male connector. Accordingly, the second connector 642 may be separated from or coupled to the first connector 622 .
- the pick-up coil 601 may be a first-order axial gradiometer. Therefore, a length of a bobbin, around which the pick-up coil 601 a is wound, may be increased.
- the pick-up coil 601 may include a pair of one-turn coils continuously connected and wound in directions opposite to each other.
- the pick-up coil 601 and the SQUID sensor 646 are bonded to be directly connected to each other using a connection line 648 of a thermally treated superconducting material, and an integral-type QUID magnetometer may be manufactured.
- a material of the pick-up coil 601 may be a niobium-tantalum (NbTi) wire.
- connection line of a niobium (Nb) material, used for bonding may be subject to a vacuum heat treatment at a temperature 1900 degrees Celsius to increase ductility.
- Superconducting bonding may be performed using an ultrasonic wedge bonder. Both end portions of the pick-up coil may be twisted together. Accordingly, noise of the pick-up coil may be significantly reduced.
- the pick-up coil may be a first-order gradiometer or a magnetometer.
- the bobbin fixing means 650 may be inserted into a through-hole 638 penetrating through a central axis of the bobbin 630 . Thus, the bobbin fixing means 650 may be fixed to a lower surface of the fixed block 610 .
- the bobbin fixing means 650 may include a non-magnetic material such as G10 epoxy.
- the bobbin fixing means 650 may be removed to replace the SQUID PCB 640 .
- the bobbin 630 and the fixed block 610 may be separated from each other.
- the malfunctioning SQUID PCB may be simply replaced with a new SQUID PCB. As a result, maintenance may be facilitated.
- the SQUID sensor module 103 a / 103 b may include a fixed block 610 having one end fixed to a support portion, a bobbin 630 having one end coupled to the other end of the fixed block 610 and having a groove around which a pick-up coil 601 a is wound, a bobbin fixing means fixed to the other end of the fixed block 610 through a through-hole formed in a center of the bobbin 630 , a superconducting quantum interference device (SQUID) printed circuit board (PCB) 640 including a SQUID sensor, and a signal line connection PCB 620 inserted into an external circumferential surface of the fixed block 610 and transferring a signal, detected by the SQUID sensor, to an external circuit.
- SQUID superconducting quantum interference device
- FIG. 14 is a perspective view illustrating a SQUID sensor module according to another example embodiment of the present disclosure.
- a first reference SQUID sensor module 105 a may be disposed on a first sensor-mounted helmet 322
- a second reference SQUID sensor module 105 b may be disposed on a second sensor-mounted helmet 332 .
- the first reference SQUID sensor module 105 a may be used as a sensor measuring a background magnetic field while the second SQUID sensor module 103 b is operating.
- the second reference SQUID sensor module 105 b may be used as a sensor measuring a background magnetic field while the first SQUID sensor module 103 a is operating.
- Each of the first reference SQUID sensor module 105 a and the second reference SQUID sensor module 105 b may be a triaxial magnetic field sensor.
- Each of the first reference SQUID sensor module 105 a and the second reference SQUID sensor module 105 b may include a first pick-up coil 743 a detecting a magnetic field component in an x-axis direction, a second pick-up coil 743 b detecting a magnetic field component in a y-axis direction, and a third pick-up coil 743 c detecting a magnetic field component in a z-axis direction.
- Each of the first to third pick-up coils 743 a to 743 c may be connected to the SQUID sensor 746 .
- the first reference SQUID sensor module 105 a may include a cylindrical fixed block 741 and a bobbin 742 in which a pick-up coil, coupled to the fixed block 741 , is disposed.
- the bobbin 742 may have a rectangular parallelepiped shape.
- the fixed block 741 may have through-holes in a plurality of central-axis directions, and litz wires 12 may be inserted into the through-holes.
- the litz wires 12 may be connected to a main thermal anchor 170 .
- a magnetoencephalography (MEG) measuring apparatus may measure magnetoencephalography of children's MEG or adults' MEG according to a rotation state using a helmet for children and a helmet for adults, respectively disposed on both ends of a barrel-shaped Dewar placed horizontally in a narrow magnetically shielded room.
- MEG magnetoencephalography
- a magnetoencephalography (MEG) measuring apparatus may efficiently block radiant heat using a neck portion having a double-wall structure in a barrel-shaped Dewar placed horizontally.
- a magnetoencephalography (MEG) measuring apparatus may measure children's MEG or adults' MEG according to a rotation state by placing a rotational motion unit, providing a rotational motion, on the ground in a barrel-shaped Dewar disposed horizontally.
- a magnetoencephalography (MEG) measuring apparatus may increase efficiency of a condenser or a cooler by transferring a low-temperature refrigerant to the condenser while providing a rotation motion using a coaxial dual-tube structure connecting the condenser and a Dewar to each other.
- a magnetoencephalography (MEG) measuring apparatus may employ a coil-in-vacuum structure, and thus, may decrease a distance between a SQUID sensor and a current source to increase a signal-to-noise ratio (SNR).
- SNR signal-to-noise ratio
- a magnetoencephalography measuring apparatus may include a main thermal anchor for cooling a SQUID sensor on a lower surface of an internal container storing a refrigerant.
- the main thermal anchor may include a plurality of components to increase a thermal contact area while inhibiting damage to the internal container caused by thermal expansion.
- a litz wire and the SQUID sensor may be efficiently cooled.
Abstract
Description
- This application is a continuation of and claims priority to PCT/KR2021/002437 filed on Feb. 26, 2021, which claims priority to Korea Patent Application No. KR 10-2020-0066113 filed on Jun. 1, 2020, the entireties of which are both hereby incorporated by reference.
- The present disclosure relates to a magnetoencephalography apparatus and, more particularly, to a magnetoencephalography apparatus provide with dual helmets.
- A magnetoencephalography apparatus is an apparatus for measuring magnetic signals generated by microcurrent of cerebral neural circuits, and is used to study brain functions and to diagnose functional brain diseases.
- In general, a magnetoencephalography signal has an amplitude of 10 fT to 1 pT and has a frequency of 0.1 to 1 kHz. Accordingly, there is a requirement for a magnetic sensor having improved sensitivity and a technology to cancel environmental magnetic noise. At present, a magnetic sensor which is most advantageous in practical terms is a superconducting quantum interference device (SQUID) based on a low-temperature superconductor niobium (Nb).
- Since Nb used for a low-temperature superconducting SQUID has a critical temperature of 9 K, cooling using liquid helium or a low-temperature freezer is required. Current magnetoencephalography apparatuses need to supplement liquid helium. Optimization of a structure, a thickness, and an installing method of a material is required to reduce thermal magnetic noise, caused by a superinsultion and thermal shield installed in a Dewar vacuum portion, while reducing an evaporation rate of a Dewar. In addition, since helium gas tends to easily pass through a small gap, high density of glass fiber reinforced plastics, used as a material of the Dewar, is required.
- Since the intensity of a magnetic signal from a magnetic field signal source decreases in inverse proportion to the square of a distance, a distance between the signal source and a pick-up coil needs to be significantly reduced to increase a signal-to-noise ratio (SNR). Research into such a method has been conducted to develop and use a coil-in-vacuum (CIV) SQUID in which a pick-up coil is disposed in a vacuum vessel.
- In a CIV SQUID apparatus, a pick-up coil and a SQUID sensor are disposed to be maintained in a vacuum state. Accordingly, only a low-temperature refrigerant is present in an internal helium storage container for storing a liquid refrigerant. Accordingly, there is only a path to fill the refrigerant. Accordingly, a diameter of a neck portion of the internal helium storage container may be significantly reduced. As a result, an evaporation rate of the liquid refrigerant may be reduced.
- An aspect of the present disclosure is to provide a coil-in-vacuum and dual-helmet structure, capable of measuring both adults and children in a single magnetoencephalography apparatus measuring device.
- Another aspect of the present disclosure is to provide a cooling apparatus having a dual-wall structure, capable of blocking radiant heat.
- Another aspect of the present disclosure is to provide a coolant tube structure having a coaxial dual-tube structure, capable of providing a rotational motion of a Dewar.
- Another aspect of the present disclosure is to provide a cooling device, capable of recycling a refrigerant.
- Another aspect of the present disclosure is to provide a magnetoencephalography measuring apparatus including two helmets.
- A dual-helmet magnetoencephalography measuring apparatus according to an example embodiment includes: an internal container storing a liquid refrigerant; an external container disposed to surround the internal container and including a first external helmet and a second external helmet disposed to be spaced apart from each other; a first sensor-mounted helmet disposed to surround the first external helmet between the external container and the internal container; a second sensor-mounted helmet disposed to surround the second external helmet between the external container and the internal container; a plurality of first SQUID sensor module disposed on the first sensor-mounted helmet; and a plurality of second SQUID sensor module disposed on the second sensor-mounted helmet. A space between the external container and the internal container is in a vacuum state.
- In an example embodiment, the external container may branch off in the form of T. The external container may include a first branch and a second branch branching off from a cylindrical external container body portion in the form of T. Each of the first external helmet and the second external helmet may be coupled to the first branch and the second branch, respectively. The first external helmet and the second external helmet may face each other and may have different sizes.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a rotational motion unit rotating the internal container and the external container about a central axis of the rotational motion unit.
- In an example embodiment, the internal container may include: a neck portion into which a baffle insert is inserted; and an internal body portion having an increased diameter as compared with the neck portion. The neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- In an example embodiment, the neck portion may further include a heat shielding layer disposed between the internal cylinder and the external cylinder.
- In an example embodiment, the internal cylinder may further include a plurality of ring projections protruding outwardly of the internal cylinder. Thermal anchors may be coupled to the ring projections, respectively. The ring projections may be disposed to be spaced apart from each other. The external cylinder may be separated with the ring projection interposed therebetween.
- In an example embodiment, an external circumferential surface of the ring projection and an internal circumferential surface of the thermal anchor may be screw-coupled to each other.
- In an example embodiment, the thermal anchor may include a cylindrical thermal anchor coupling portion and a disc-shaped thermal anchor body portion disposed on an external circumferential surface of the thermal anchor coupling portion. An internal circumferential surface of the thermal anchor coupling portion may be screw-coupled to an external circumferential surface of the ring projection.
- In an example embodiment, the internal container may include: a neck portion into which a baffle insert is inserted; and a body portion having a diameter increased as compared to the neck portion. The dual-helmet magnetoencephalography measuring apparatus may further include: a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporated refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant; and a condenser connected to the refrigerant exhaust tube and the refrigerant injection tube and condensing an evaporated refrigerant exhausted through the refrigerant injection tube. The refrigerant injection tube may have a coaxial structure inserted into the refrigerant exhaust tube.
- In an example embodiment, each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a C-shaped external container support portion supporting lower surfaces of the first branch and the second branch; and a rotational motion unit coupled to the external container support portion to provide a rotational motion to the external container.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a vacuum-sealing portion inserted into a through-hole formed in the lower surface of each of the first and second branches to seal signal lines and disposed inside the external container support portion; and a signal line connection box disposed below the external container support portion and connecting the signal lines, sealed through the vacuum-sealing portion, to each other. The rotational motion unit may further include: an upper base box disposed to surround the signal line connection box; a lower base box disposed below the upper base box; and a bearing portion disposed between the upper base box and the lower base box to provide a rotational motion to the upper base box.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a handle coupled to an external side of the upper base box.
- In an example embodiment, the first external helmet may include a coupled portion provided with a long groove. The first external helmet may be coupled to one end of the first branch while rotating along the long groove in an aligned state. The second external helmet may include a coupled portion provided with a long grove. The second external helmet may be coupled to one end of the second branch while rotating along the long groove in an aligned state.
- In an example embodiment, the internal container may include: a neck portion into which a baffle insert is inserted; a first body portion having an increased diameter as compared with the neck portion; a second body portion having an increased diameter as compared with the first body portion; and a third body portion having a decreased diameter as compared with the second body portion.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a pair of first support portions coupled to an interface between the neck portion and the first body portion and respectively extending in a direction of the first external helmet and a direction of the second external helmet; a pair of second support portion coupled to an interface between the first body portion and the second body portion and respectively extending in the direction of the first external helmet and the direction of the second external helmet; a pair of third support portion coupled to an interface between the second body portion and the third body portion and respectively extending in the direction of the first external helmet and the direction of the second external helmet; a first fixing ring coupled to the first, second, and third support portions in the direction of the first external helmet; a second fixing ring coupled to the first, second, and third support portion in the direction of the second external helmet; a first auxiliary fixing part connecting the first fixing ring and the first sensor-mounted helmet; and a second auxiliary fixing part connecting the second fixing ring and the second senso-mounted helmet.
- In an example embodiment, each of the first, second, and third support portions may include a plurality of arc long grooves. A coupling member may be inserted into each of the arc long grooves to be coupled to the internal container.
- In an example embodiment, the first sensor-mounted helmet may include: a helmet body having an open region for securing a view; a lower brim disposed along an edge of a lower surface of the helmet body; an upper brim providing a brim in the open portion of the helmet body; a helmet fixing ring having a ring shape at a predetermined interval from the lower brim and continuously connected to the upper brim; and a plurality of connection pillars vertically connecting the lower brim and the upper brim to each other.
- In an example embodiment, the dual-helmet magnetoencephalography measuring apparatus may further include: a first auxiliary thermal anchor disposed on a lower surface of each of the upper brim and the lower brim of the first sensor-mounted helmet; a first internal 4K heat shielding portion being in thermal contact with the first auxiliary thermal anchor and disposed on an internal side surface of the first sensor-mounted helmet; and a first external 4K heat shielding portion being in thermal contact with the first auxiliary thermal anchor and disposed on an external side surface of the first sensor-mounted helmet. The first auxiliary thermal anchor, the first internal 4K heat shielding portion, and the first external 4K heat shielding portion may be in thermal contact with a main thermal anchor by a litz wire.
- In an example embodiment, each of the plurality of first SQUID sensor modules may be in thermal contact with a main thermal anchor disposed on a lower surface of the internal container through a litz wire. Each of the plurality of second SQUID sensor modules may be in thermal contact with the main thermal anchor disposed on the lower surface of the internal container through a litz wire.
- In an example embodiment, the first SQUID sensor modules may be cooled by a plural of litz wires. Some of the plurality of litz wires may be connected to first SQUID sensor modules arranged around the first SQUID sensor module, and the remainder of the plurality of litz wires may be in thermal contact with a main thermal anchor.
- In an example embodiment, the first SQUID sensor module may be cooled by six litz wires. Among the six litz wires, two litz wires may be in thermal contact with the main thermal anchor, and four litz wires may be connected to the first SQUID sensor modules arranged around the first SQUID sensor module.
- In an example embodiment, the internal container may include a neck portion into which a baffle insert is inserted. The neck portion may have a double-wall structure. Washer-shaped first to third thermal anchors, disposed to be vertically spaced apart from each other, may be provided on an external side of the neck portion. The first thermal anchor may be connected to a 120K heat shielding layer. The second thermal anchor may be connected to an 80K heat shielding layer. The third thermal anchor may be connected to a 40K heat shielding layer.
- In an example embodiment, the 40K heat shielding layer may be disposed to surround the first sensor-mounted helmet and the second sensor-mounted helmet.
- In an example embodiment, the first SQUID sensor module may be inserted into a through-hole, formed in the first sensor-mounted helmet, to be fixed. The first SQUID sensor module may include a plurality of holes. Litz wires may be respectively inserted into the holes to cool a SQUID sensor.
- In an example embodiment, the main thermal anchor may include: a first heat transfer unit formed of oxygen-free copper and including a first disc, a first upper projection protruding from a central axis of the first disc to an upper surface of the first disc, and a first lower projection protruding from the central axis of the first disc to a lower surface of the first disc; a second heat transfer unit formed of oxygen-free copper and including a second disc, a second upper projection protruding from a central axis of the second disc to an upper surface of the second disc, and a second lower projection protruding from the central axis of the second disc to a lower surface of the second disc; a third heat transfer unit formed of oxygen-free copper and including a third disc, a third upper projection protruding from a central axis of the third disc to an upper surface of the third disc, and a third lower projection protruding from the central axis of the third disc to a lower surface of the third disc; a fourth heat transfer unit formed of oxygen-free copper and including a fourth disc, a fourth upper projection protruding from a central axis of the fourth disc to an upper surface of the fourth disc, and a fourth lower projection protruding from the central axis of the fourth disc to a lower surface of the fourth disc; a fifth heat transfer unit, formed of oxygen-free copper, coupled to the fourth heat transfer unit and having a strip shape; a first thermal expansion control unit formed of an insulating material and inserted between the first disc of the first heat transfer unit and the second disc of the second heat transfer; and a second thermal expansion control unit formed of an insulating material and inserted between the third disc of the third heat transfer unit and the fourth disc of the fourth heat transfer unit. The second upper projection of the second heat transfer unit may be provided with a groove for coupling to the first lower projection of the first heat transfer unit. The second lower projection of the second heat transfer unit may be provided with a groove for coupling to the third upper projection of the third heat transfer unit. The third lower projection of the third heat transfer unit may be provided with a groove for coupling to the fourth upper projection of the fourth heat transfer unit.
- In an example embodiment, the first thermal expansion control unit may include: a first insulating body portion having the same diameter as a first diameter of the first disc; a second insulating body portion embedded in a lower surface of the internal container and having a second diameter greater than the first diameter; and a third insulating body portion having a third diameter smaller than the second diameter. The third insulating body portion may be disposed to surround an external circumferential surface of the second disc.
- A magnetic field measuring apparatus according to an example embodiment includes: an external container; and a cylindrical internal container storing a liquid refrigerant and inserted into the external container. The internal container includes: a neck portion into which a baffle insert is inserted; and a body portion having an increased diameter as compared with the neck portion. The neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- In an example embodiment, the internal cylinder may further include a plurality of ring projections protruding outwardly of a cylinder. Thermal anchors may be coupled to the ring projections, respectively. The ring projections may be disposed to be spaced apart from each other. The external cylinder may be separated with the ring projection interposed therebetween.
- In an example embodiment, the neck portion may further include a heat shielding layer disposed between the internal cylinder and the external cylinder.
- In an example embodiment, an external circumferential surface of the ring projection and an internal circumferential surface of the thermal anchor may be screw-coupled to each other.
- In an example embodiment, each of the thermal anchors may include a disc-shaped thermal anchor body portion disposed on both a cylindrical thermal anchor coupling portion and on an external circumferential surface of the thermal anchor coupling portion. An internal circumferential surface of the thermal anchor coupling portion may be screw-coupled to an external circumferential surface of the ring projection.
- In an example embodiment, the thermal anchors may include first to third thermal anchors. The first thermal anchor may be connected to a 120K heat shielding layer, the second thermal anchor may be connected to an 80K heat shielding layer, and the third thermal anchor may be connected to a 40K heat shielding layer.
- In an example embodiment, the magnetic field measuring apparatus may further include: a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporate refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant;
- and a condenser connected to the refrigerant exhaust tube and the refrigerant injection tube and condensing an evaporated refrigerant exhausted through the refrigerant injection tube. The refrigerant injection tube may provide a coaxial structure to be inserted into the refrigerant exhaust tube. Each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- A magnetic field measuring apparatus according to an example embodiment include: an external container; a cylindrical internal container storing a liquid refrigerant and inserted into the external container; a baffle inserted into the internal container; a refrigerant exhaust tube disposed at the baffle insert and exhausting an evaporated refrigerant; a refrigerant injection tube disposed at the baffle insert and injecting a refrigerant; and a condenser connected to the refrigerant exhaust tube and the refrigerant injection tube and condensing an evaporate refrigerant exhausted through the refrigerant injection tube. The refrigerant injection tube may have a coaxial structure inserted into the refrigerant exhaust tube. Each of the refrigerant exhaust tube and the refrigerant injection tube may be a dual tube including an internal tube and an external tube.
- In an example embodiment, the internal container may include: a neck portion where the baffle is inserted; and a body portion having an increased diameter as compared with the neck portion. The neck portion may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder.
- A magnetic field measuring apparatus according to an example embodiment include: an external container; a cylindrical internal container storing a liquid refrigerant and inserted into the external container; a main thermal anchor disposed on a lower surface of the internal container; and a plurality of first SQUID sensor modules disposed on an external side of the internal container. Each of the plurality of first SQUID sensor modules may be in thermal contact with a main thermal anchor, disposed on a lower surface of the internal container, through a litz wire.
- In an example embodiment, the main thermal anchor may include: a first heat transfer unit formed of oxygen-free copper and including a first disc, and a first lower projection protruding from the central axis of the first disc to a lower surface of the first disc; a second heat transfer unit formed of oxygen-free copper and including a second disc, a second upper projection protruding from a central axis of the second disc to an upper surface of the second disc, and a second lower projection protruding from the central axis of the second disc to a lower surface of the second disc; a third heat transfer unit formed of oxygen-free copper and including a third disc, a third upper projection protruding from a central axis of the third disc to an upper surface of the third disc, and a third lower projection protruding from the central axis of the third disc to a lower surface of the third disc; a fourth heat transfer unit formed of oxygen-free copper and including a fourth disc, a fourth upper projection protruding from a central axis of the fourth disc to an upper surface of the fourth disc; a first thermal expansion control unit formed of an insulating material and inserted between the first disc of the first heat transfer unit and the second disc of the second heat transfer; and a second thermal expansion control unit formed of an insulating material and inserted between the third disc of the third heat transfer unit and the fourth disc of the fourth heat transfer unit. The second upper projection of the second heat transfer unit may be provided with a groove for coupling to the first lower projection of the first heat transfer unit. The second lower projection of the second heat transfer unit may be provided with a groove for coupling to the third upper projection of the third heat transfer unit. The third lower projection of the third heat transfer unit may be provided with a groove for coupling to the fourth upper projection of the fourth heat transfer unit.
- In an example embodiment, the first thermal expansion control unit may include: a first insulating body portion having the same diameter as a first diameter of the first disc; a second insulating body portion embedded in a lower surface of the internal container and having a second diameter greater than the first diameter; and a third insulating body portion having a third diameter smaller than the second diameter. The third insulating body portion may be disposed to surround an external circumferential surface of the second disc.
- The present disclosure will become more apparent in view of the attached drawings and accompanying detailed description. The embodiments depicted therein are provided by way of example, not by way of limitation, wherein like reference numerals refer to the same or similar elements. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating aspects of the present disclosure.
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FIG. 1 is a conceptual diagram illustrating a magnetoencephalography measuring apparatus according to an example embodiment of the present disclosure. -
FIG. 2 is a perspective view illustrating a magnetoencephalography measuring apparatus. -
FIG. 3 is a cross-sectional view taken along line A-A′ inFIG. 2 . -
FIG. 4 is a perspective view illustrating an internal container and a sensor-mounted helmet. -
FIG. 5 is an exploded perspective view illustrating a rotational motion unit supporting an external container and providing a rotational motion. -
FIG. 6 is an enlarged cross-sectional view of the internal container of the magnetoencephalography measuring apparatus. -
FIG. 7 is a perspective view illustrating a support portion of the sensor-mounted helmet of the magnetoencephalography measuring apparatus. -
FIG. 8 is a view when viewed from a lower surface of the internal container of the magnetoencephalography measuring apparatus. -
FIG. 9 is a perspective view illustrating a sensor-mounted helmet according to an example embodiment of the present disclosure. -
FIG. 10 is a cross-sectional view of the sensor-mounted helmet ofFIG. 9 . -
FIG. 11 is a conceptual diagram illustrating a connection relationship between a main thermal anchor and a SQUID sensor module according to an example embodiment of the present disclosure. -
FIG. 12 is a cross-sectional view of the main thermal anchor. -
FIG. 13A is a perspective view illustrating a SQUID sensor module according to an example embodiment of the present disclosure. -
FIG. 13B is an exploded perspective view illustrating the SQUID sensor module ofFIG. 13A . -
FIG. 13C is a cross-sectional view illustrating a SQUID sensor module according to an example embodiment of the present disclosure. -
FIG. 14 is a perspective view illustrating a SQUID sensor module according to another example embodiment of the present disclosure. - According to an example embodiment, a technology for directly recondensing a helium gas using a refrigerator and resending the recondensed helium gas to a Dewar is applied. Since magnetic noise and vibration noise caused by the refrigerator and refrigerant delivery tube are significantly large, a special Dewar structure and a special SQUID arrangement method are required to prevent a SQUID from reacting with vibrations. In particular, a stable structure for supporting a SQUID-mounted helmet is required.
- With the recent increase in the price of helium gas, a technology for directly recondensing a helium gas using a refrigerator and resending the recondensed helium gas to a magnetoencephalography Dewar is required. Vaporized helium is supplied to a refrigerator through a refrigerant exhaust tube, and a liquefied refrigerant is supplied to a Dewar through a refrigerant injection tube. When the refrigerant exhaust tube and the refrigerant injection tube include a single pipe, ice is condensed on a baffle insert lid. Such ice inhibits perfect sealing to causes lots of external heat influx.
- A CIV SQUID according to an example embodiment addresses an issue regarding ice condensation on a baffle insert lid using a coaxial dual-tube structure. A refrigerant exhaust tube and a refrigerant injection tube have a coaxial structure, and each of the refrigerant exhaust tube and the refrigerant injection tube has a dual-tube structure. The dual-tube structure may prevent moisture condensation occurring on a surface of an upper plate of a Dewar. Accordingly, rotation of the Dewar may be provided using a sealing member such as an O-ring. In addition, the dual-tube structure may transfer a temperature of an evaporated helium gas to a cooler in a cold state, and thus, efficiency of the cooler may be improved.
- In the CIV SQUID, the Dewar includes an internal container and an external container surrounding the internal container. However, the internal container absorbs radiant heat externally to increase consumption of a refrigerant.
- In the CIV SQUID, the Dewar uses a double-wall structure in a neck portion of the internal container into which a baffle insert is inserted. Such a double-wall structure improves mechanical stability resulting from thermal expansion. In addition, a heat shielding layer disposed between the double walls reduces influx of radiant heat. In addition, a thermal anchor disposed on the outside of the double-wall structure uses a screw coupling to reduce damage caused by thermal expansion while being in thermal contact with an internal wall of the internal container having a double-wall structure through a large contact area. The double-wall structure may reduce an evaporation rate of the refrigerant and may stably support an internal structure with a high load, allowing internal vibration caused by evaporation of the refrigerant to be reduced.
- A magnetoencephalography (MEG) signal depends on a distance between a SQUID sensor and a brain. Therefore, an MEG helmet for adults is not suitable to measure MEG of children. Accordingly, there is a need for a dual helmet in which a single MEG apparatus can measure both adults and children.
- A helmet for children may be provided with 144 channels, and a helmet for adults may be provided with 192 channels. Therefore, as a structure optimal for a head size, it is expected that the quality of, in particular, children's MEG signals will be improved. It is advantageous to measure development processes of children's brain functions to adults' brain functions.
- A magnetoencephalography apparatus according to an example embodiment has a structure in which two helmets are disposed on a single Dewar. A helmet for children and a helmet for adults, having different sizes, are mounted to face each other.
- In a magnetoencephalography apparatus according to an example embodiment, each of a helmet for children and a helmet for adults may measure magnetoencephalography in a lying state according to a rotation state of a Dewar. To provide a rotational motion of the Dewar, a rotational motion unit may provide a rotation motion of the Dewar using a non-metallic bearing. The rotational motion unit may include a signal line connection box, to which signal lines are connected, therein.
- A magnetoencephalography apparatus according to an example embodiment includes a main thermal anchor disposed on a lower surface of an internal container. The main thermal anchor includes a plurality of heat transfer portions, screw-coupled to each other, and a thermal expansion control portion formed of an insulating material and controlling sealing failure caused by thermal expansion between the heat transfer portion and the internal container. When the plurality of heat transfer portions are coupled to each other, a pair of thermal expansion control portions, disposed to be embedded in an external surface and an internal surface of the internal container, are pressed to inhibit damage to components caused by sealing and thermal expansion.
- Hereinafter, embodiments of the present disclosure will be described below more fully with reference to accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.
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FIG. 1 is a conceptual diagram illustrating a magnetoencephalography measuring apparatus according to an example embodiment of the present disclosure. -
FIG. 2 is a perspective view illustrating a magnetoencephalography measuring apparatus. -
FIG. 3 is a cross-sectional view taken along line A-A′ inFIG. 2 . -
FIG. 4 is a perspective view illustrating an internal container and a sensor-mounted helmet. -
FIG. 5 is an exploded perspective view illustrating a rotational motion unit supporting an external container and providing a rotational motion. -
FIG. 6 is an enlarged cross-sectional view of the internal container of the magnetoencephalography measuring apparatus. - Referring to
FIGS. 1 to 6 , amagnetoencephalography measuring apparatus 300 includes aninternal container 360 storing a liquid refrigerant, anexternal container 310 disposed to surround theinternal container 360 and including a firstexternal helmet 320 and a secondexternal helmet 330 disposed to be spaced apart from each other, a first sensor-mountedhelmet 322 disposed to surround the firstexternal helmet 320 between theexternal container 310 and theinternal container 360, a second sensor-mountedhelmet 332 disposed to surround the secondexternal helmet 330 between theexterna container 310 and theinternal container 360, a plurality of firstSQUID sensor module 103 a disposed on the first sensor-mountedhelmet 322, and a plurality of secondSQUID sensor module 103 b disposed on the second sensor-mountedhelmet 332. A space between theexternal container 310 and theinternal container 360 is in a vacuum state. - Each of the plurality of first
SQUID sensor modules 103 a is in thermal contact with a mainthermal anchor 170 disposed on a lower surface of theinternal container 360 through alitz wire 12. Each of the plurality of secondSQUID sensor modules 103 b is in thermal contact with the mainthermal anchor 170 disposed on the lower surface of theinternal container 360 through thelitz wire 12. The space between theexternal container 310 and theinternal container 360 is in a vacuum state. The SQUID sensor of the first helmet-mountedsensor 322 and the second helmet-mountedsensor 332 may be efficiently cooled through thelitz wire 12. - The
magnetoencephalography measuring apparatus 300 may be disposed inside a magnetically shieldedroom 11. - The
external container 310 may branch off in the form of T. Theexternal container 310 may include afirst branch 312 and asecond branch 314 branching off from a cylindrical externalcontainer body portion 316 in the form of T. Each of the firstexternal helmet 320 and the secondexternal helmet 330 may be coupled to thefirst branch 312 and thesecond branch 314, respectively. The firstexternal helmet 320 and the secondexternal helmet 330 may face each other and may have different sizes. A diameter of each of thefirst branch 312 and thesecond branch 314 may be greater than a diameter of the externalcontainer body portion 316. The firstexternal helmet 320 may include anopen portion 321 for securing a view. The externalcontainer body portion 316 may be vertically disposed, and thefirst branch 312 and thesecond branch 314 may be horizontally disposed. Theexternal container 310 may be a glass fiber reinforced plastic such as G10 epoxy. - The external
container body portion 316 may have a cylindrical shape and may rotate about a central axis thereof. The firstexternal helmet 320 or the firstexternal helmet 320 may measure a magnetoencephalography signal for children or adults according to a rotation state of theexternal container 310. - A
rotational motion unit 340 may be coupled to lower surfaces of thefirst branch 312 and thesecond branch 314. Therotational motion unit 340 may include a bearing formed of a non-conductive material. Therotational motion unit 340 may be mounted on a bottom of the magnetically shieldedroom 11. - The first
external helmet 320 may be provided with along groove 320 a in a portion coupled to thefirst branch 312. The firstexternal helmet 320 may rotate along thelong groove 320 a to be coupled to one end of thefirst branch 312 in a state of being aligned therewith. - The
long groove 320 a may provide alignment between the firstexternal helmet 320 and the first sensor-mountedhelmet 322. The firstexternal helmet 320 may include theopen portion 321 for securing a view. - The second
external helmet 330 may be provided with a long groove in a portion coupled to thesecond branch 314. The secondexternal helmet 330 may rotate along the long groove to be coupled to one end of thesecond branch 314 in a state of being aligned therewith. - The
internal container 360 may store a liquid refrigerant, and may cool theSQUID sensor modules thermal anchor 170 and thelitz wire 12. A material of theinternal container 360 may be a glass fiber reinforced plastic such as G10 epoxy. - The
internal container 360 may include aneck portion 362 into which abaffle insert 150 is inserted, afirst body portion 364 having an increased diameter as compared with theneck portion 362, asecond body portion 366 having an increased diameter as compared with thefirst body portion 364; and athird body portion 368 having a decreased diameter as compared with the second body portion. Theinternal container 360 may include a body portion and aneck portion 362 into which thebaffle insert 150 is inserted. The body portion may include afirst body portion 364 having an increased diameter as compared with theneck portion 362, asecond body portion 366 having an increased diameter as compared with the first body portion, and athird body portion 368 having a decreased diameter as compared with the second body portion. - The
neck portion 362 may have a double-wall structure including an internal cylinder and an external cylinder surrounding the internal cylinder. Thefirst body portion 364 may be continuously connected to theneck portion 362. Thesecond body portion 366 may be continuously connected to thefirst body portion 364. Thesecond body portion 366 may have a greater diameter than thefirst body portion 364. Thethird body portion 368 may be continuously connected to thesecond body portion 366. Thethird body portion 368 may have a smaller diameter than thesecond body portion 366. Thefirst body portion 364 and thethird body portion 368 may have the same diameter. - The first sensor-mounted
helmet 322 and the second sensor-mountedhelmet 332 are arranged symmetrically with respect to the first tothird body portions - A
lower surface 368 a of thethird body portion 368 may include a plurality ofgetter grooves 368 b having a fan shape in a direction toward a lower surface or a vacuum side. A getter, collecting residual gas in a vacuum state, may be disposed in thegetter groove 368 b. - The
neck portion 362 may include aninternal cylinder 162 a and anexternal cylinder 162 b surrounding theinternal cylinder 162 a. Theheat shielding film 162 c may be disposed between theinternal cylinder 162 a and theexternal cylinder 162 b. Theheat shielding layer 162 c may have a multilayer structure in which a metal thin film, having high reflectivity and low emissivity, and a significantly thin nonwoven fabric, having low thermal conductivity, are sequentially stacked. - The
internal cylinder 162 a may further include a plurality ofring projections 162 a′ protruding outwardly of a cylinder. Thering projection 162 a′ may have a cylindrical ring shape, and may be formed to be integrated with theinternal cylinder 162 a. A screw for screw-coupling may be formed on an external circumferential surface of thering projection 162 a′. - The
ring projections 162 a′ may be disposed to be spaced apart from each other. Theexternal cylinder 162 b may be separated with thering projection 162 a′ interposed therebetween. That is, theexternal cylinder 162 b may include a plurality of cylindrical components separated from each other. A distance between theexternal cylinder 162 b and theinternal cylinder 162 a may be within several millimeters (mm). Each of theexternal cylinders 162 a may have a raised spot to surround a thermalanchor coupling portion 106 a″ and thering projection 162 a′. Theexternal cylinder 162 b may be coupled to surround thering projection 162 a′, a coupling portion may be fixed and sealed with an adhesive such as epoxy. - The thermal anchors 106 a, 106 b, and 106 c may be coupled to the
ring projections 162 a′, respectively. An external circumferential surface of thering projection 162 a′ and the internal circumferential surface of thethermal anchors thermal anchors thermal anchors - The
thermal anchor 106 a may include a cylindrical thermalanchor coupling portion 106 a″ and a disc-shaped thermalanchor body portion 106 a′ disposed on an external circumferential surface of the coupling portion. An internal circumferential surface of the thermalanchor coupling portion 106 a″ may be screw-coupled to the external circumferential surface of thering projection 162 a′. Accordingly, thethermal anchors - The screw-coupling of the
ring projection 162 a′ and thethermal anchor 106 a may improve mechanical stability while providing efficient thermal contact caused by thermal expansion. - The double-wall structure may prevent radiant heat from flowing into the
internal container 360 from an external entity. When the internal container is cooled by the refrigerant, a space between the internal cylinder and the external cylinder may be maintained in a vacuum state. Accordingly, heat influx caused by heat transfer may be blocked, and theheat shielding layer 162 c may additionally block the influx of the radiant heat. Accordingly, a neck portion of the double-wall structure may provide high mechanical stability and high heat shielding efficiency, as compared with to a neck portion of a single-wall structure. - The thermal anchors 106 a, 106 b, and 106 c may include first to third
thermal anchors thermal anchor 106 a may be disposed on an uppermost side of theneck portion 362, and may be connected to a 120Kheat shielding layer 107 a. The secondthermal anchor 106 b may be disposed under the firstthermal anchor 106 a and connected to an 80Kheat shielding layer 107 b. The thirdthermal anchor 106 c may be disposed on a lower side of the secondthermal anchor 106 b, and may be connected to a 40Kheat shielding layer 107 c. An external diameter of the firstthermal anchor 106 a may be greater than an external diameter of the secondthermal anchor 106 b. - The first
thermal anchor 106 a may be spaced farthest apart from the refrigerant to be maintained at a highest temperature, and the thirdthermal anchor 106 c may be closest to the refrigerant to be maintained at a lowest temperature. The first to thirdthermal anchors - The 40K
heat shielding layer 107 c may be coupled to an external circumferential surface of the thirdthermal anchor 106 c, and may be disposed to surround theinternal container 360 to block the influx of radiant heat. - The 40K
heat shielding layer 107 c may include a heat insulating layer a metal mesh woven with metal wires insulated from each other. The 40Kheat shielding layer 107 c may branch off in the form of T to surround the first sensor-mountedhelmet 322 and the second sensor-mountedhelmet 332, and then may surround the first sensor-mountedhelmet 322 and the second sensor-mounted helmet 133. - The 80K
heat shielding layer 107 b may be coupled to an external circumferential surface of thesecond heat anchor 106 b, and may be disposed to surround the 40Kheat shielding layer 107 c and to block the influx of radiant heat. The 80Kheat shielding layer 107 b may include a heat insulating layer and a metal mesh woven with metal wires insulated from each other. The80K heat shield 107 b may branch into in the form of T to surround the first sensor-mountedhelmet 322 and the second sensor-mountedhelmet 332. The80K heat shield 107 b may extend in a direction of a brim of the first sensor-mountedhelmet 322, and may extend in a direction of a brim of the second sensor-mountedhelmet 332. - The 120K
heat shielding layer 107 a may be coupled to an external circumferential surface of thefirst heat anchor 106 a, and may be disposed to surround the 80Kheat shielding layer 107 b and to block the influx of radiant heat. The 120Kheat shielding layer 107 a may include a heat insulating layer and a metal mesh woven with metal wires insulated from each other. The 120Kheat shielding layer 107 a may branch off in the form of T to surround the first sensor-mountedhelmet 322 and the second sensor-mountedhelmet 332. - Each of the heat shielding layers 107 a, 107 b, and 107 c may have an opening in a direction toward the external
container support portion 341. The openings may be disposed so as not to overlap each other. Accordingly, signal lines may pass through the openings of theheat shielding layer vacuum sealing portion 344. - The space between the
internal container 360 and theexternal container 310 may be maintained in a vacuum state. Theexternal container lid 311 may include anexhaust port 311 a connected to a vacuum pump. Theexhaust port 311 a may be formed of a G-10 epoxy tube. - The
baffle insert 150 may be disposed to be inserted into theneck portion 362 of theinternal container 360. Thebaffle insert 150 may include an insertupper plate 151, abaffle 156 disposed below the insert upper plate, and a plurality ofguide rods 154 supporting thebaffle 156 and fixed to the insertupper plate 151. - The insert
upper plate 151 may have a disc shape and may be formed of G-10 epoxy. The insertupper plate 151 may be fixed to theexternal container lid 311. Theguide rod 154 is formed of G-10 epoxy, and may have a rod shape or a pipe shape. Theguide rod 154 may support thebaffle 156. Thebaffle 156 may include Styrofoam having improved warmth retention and a conductive plate. The conductive plate may include an aluminum-coated Mylar layer and a copper layer sequentially stacked to block the radiant heat. - A
refrigerant exhaust tube 153 may be disposed on the insert upper plate of thebaffle insert 150, and may exhaust the evaporated refrigerant. Therefrigerant injection tube 152 may be disposed on the insertupper plate 151 of thebaffle insert 150, and may inject a refrigerant. Each of therefrigerant exhaust tube 153 and therefrigerant injection tube 152 may be a dual tube including an internal tube and an external tube. In the dual tube, a space between the internal tube and the external tube may be maintained in a vacuum state during cooling. Therefrigerant injection tube 152 may have a coaxial structure inserted into therefrigerant exhaust tube 153. Therefrigerant exhaust tube 153 and therefrigerant injection tube 152 may be formed of G-10 epoxy. - Coaxial
dual tubes upper plate 151 to reduce ice formation of the insertupper plate 151. When the refrigerant exhaust tube and the refrigerant injection tube are a single tube, the insertupper plate 151 and the refrigerant exhaust tube may form ice to impede sealing of the external container lid 111 and the insertupper plate 151 and to increase influx of external heat. The coaxialdual tubes upper plate 151. One end of therefrigerant exhaust tube 153 may be disposed in a higher location than thefirst heat anchor 106 a. When theexternal container 310 and theinternal container 360 rotate, the coaxialdual tubes - The
condenser 159 may be connected to therefrigerant exhaust tube 153 and therefrigerant injection tube 152, and may condense the vaporized refrigerant exhausted through therefrigerant injection tube 153. Thecondenser 159 may be disposed outside the magnetically shieldedroom 11. - The
rotational motion unit 340 may be coupled to lower surfaces of thefirst branch 312 and thesecond branch 314. Therotational motion unit 340 may provide a rotational motion of theexternal container 310. - The
rotational motion unit 340 may include an externalcontainer support portion 341, anupper support box 342, alower support box 347, and a bearingportion 346. - The external
container support portion 341 may be in the form of C, and may support the lower surfaces of thefirst branch 312 and thesecond branch 314. The externalcontainer support portion 341 may have a through-hole in a center thereof. - A
vacuum sealing portion 344 may be inserted into through-holes formed in the lower surface of thefirst branch 312 and thesecond branch 314 to seal signal lines, and be disposed inside the externalcontainer support portion 341. Thevacuum sealing portion 344 may seal theexternal container 310 in a vacuum state and the outside in an atmospheric pressure state to each other. - A signal
line connection box 345 may be disposed below the externalcontainer support portion 341, and may connect the sealedsignal lines 15 to each other through thevacuum sealing portion 344. The signalline connection box 345 may be disposed inside theupper support box 342. - The
upper support box 342 may be disposed to surround the signalline connection box 345, and may have a cylindrical shape. Theupper support box 342 may support the externalcontainer support portion 341. Ahandle 343 may be coupled to an external side of theupper support box 342. A user may rotate thehandle 343 to select a rotational state of a magnetoencephalography measuring apparatus. - The
lower support box 347 may be disposed below theupper support box 342. - The bearing
portion 346 may be disposed between theupper support box 342 and thelower support box 347 to provide a rotational motion of theupper support box 342. -
FIG. 7 is a perspective view illustrating a support portion of the sensor-mounted helmet of the magnetoencephalography measuring apparatus. -
FIG. 8 is a view when viewed from a lower surface of the internal container of the magnetoencephalography measuring apparatus. -
FIG. 9 is a perspective view illustrating a sensor-mounted helmet according to an example embodiment of the present disclosure. -
FIG. 10 is a cross-sectional view of the sensor-mounted helmet ofFIG. 9 . - Referring to
FIGS. 7 to 10 , a first sensor-mountedhelmet 322 may be configured to cover a head, and may include an open portion to secure a subject's view. The first sensor-mountedhelmet 322 may includebrims 322 a′ and 322 a″ on edges thereof. Thebrim 322 a′ and 322 a″ may be connected to a fixing means for fixing the first sensor-mountedhelmet 322. - A second sensor-mounted
helmet 332 may be configured to cover a head, and includes an open portion to secure a subject's view. The second sensor-mountedhelmet 332 may include a brim on an edge thereof. The brim may be connected to a fixing means for fixing the second sensor-mountedhelmet 332. - A pair of
first support portions 382 may be coupled to an interface between theneck portion 362 and thefirst body portion 364, and may extend in a direction of the firstexternal helmet 320 and in a direction of the secondexternal helmet 330, respectively. Thefirst support portion 382 may include a C-shapedportion 382 c, coupled to the interface between theneck portion 362 and thefirst body portion 364, and a pair ofpillars 382 b extending parallel to a direction of a corresponding external helmet. The C-shapedportion 382 c may have a plurality of arc-shapedlong grooves 382 a. A fixing means may be coupled to each of the arc-shapedlong grooves 382 a to provide alignment with a corresponding sensor-mounted helmet. - A pair of
second support portions 384 may be coupled to an interface between thefirst body portion 364 and thesecond body portion 366, and extend in the direction of the firstexternal helmet 320 and in the direction of the secondexternal helmet 330, respectively. Thesecond support portion 384 may include a C-shaped portion, coupled to an interface between thefirst body portion 364 and thesecond body portion 366, and a pair of pillars extending parallel to a direction of a corresponding external helmet. The C-shaped portion may include a plurality of arc-shapedlong grooves 384 a. A fixing means may be coupled to each of the arc-shapedlong grooves 384 a to provide alignment with a corresponding sensor-mounted helmet. - A pair of
third support portions 386 may be coupled to an interface between thesecond body portion 386 and thethird body portion 388, and may extend in a direction of the firstexternal helmet 320 and in a direction of the secondexternal helmet 330, respectively. Thesecond support portion 384 may include a C-shaped portion, coupled to an interface between thesecond body portion 386 and thethird body portion 388, and a pair of pillars extending parallel to a direction of a corresponding external helmet. The C-shaped portion may include a plurality of arc-shapedlong grooves 386 a. A fixing means may be coupled to the arc-shaped long groove to provide alignment with a corresponding sensor-mounted helmet. - A
first fixing ring 387 may be coupled to thefirst support portion 382, thesecond support portion 384, and thethird support portion 386 in a direction of the firstexternal helmet 320. - A
second fixing ring 388 may be coupled to thefirst support portion 382, thesecond support portion 384, and thethird support portion 386 in a direction of the secondexternal helmet 330. - A first
auxiliary fixing part 323 may connect thefirst fixing ring 387 and the first sensor-mountedhelmet 322 to each other. The firstauxiliary fixing part 323 may include anupper ring 323 a, alower ring 323 c spaced apart from theupper ring 323 a, and a plurality ofsupport rods 323 b connecting theupper ring 323 a and thelower ring 323 c to each other. - The second auxiliary fixing part 333 may connect the
second fixing ring 388 and the second sensor-mountedhelmet 332 to each other. The second auxiliary fixing part 333 may include an upper ring, a lower ring spaced apart from the upper ring, and a plurality of support rods connecting the upper ring and the lower ring to each other. - The first sensor-mounted
helmet 322 may includebrims 322 a′ and 322 a″ on edges thereof. The first sensor-mountedhelmet 322 may have the same structure as the second sensor-mountedhelmet 332, but the first sensor-mountedhelmet 322 may be different, in size and the number of SQUID sensor modules, from the second sensor-mountedhelmet 332. The first sensor-mountedhelmet 322 may have a first through-hole 322 b for mounting a SQUID sensor module, a second through-hole 322 c for placing a signal line, and a third through-hole for mounting a fixing member for fixing theSQUID sensor module 103 a. - The first sensor-mounted
helmet 322 may include ahelmet body 322′ having an open region for securing a view, alower brim 322 a′ disposed along an edge of a lower surface of the helmet body, anupper brim 322 a″ providing a brim in the open portion of the helmet body, ahelmet fixing ring 322 f having a ring shape at a predetermined interval from thelower brim 322 a′ and continuously connected to theupper brim 322 a″, and a plurality ofconnection pillars 322 e vertically connecting thelower brim 322 a′ and theupper brim 322 a″ to each other. The brim of the first sensor-mountedhelmet 322 may include an upper brim, disposed in an open portion to secure a view, and a lower brim surrounding a subject's occipital region. - The first auxiliary
thermal anchor 185 may be disposed on a lower surface of thebrim 322 a of the first sensor-mountedhelmet 322. The first auxiliarythermal anchor 185 may be divided into a plurality ofcomponents 185 a to 185 d. The first auxiliarythermal anchor 185 may be fabricated using an oxygen-free copper strip. The divided first auxiliarythermal anchor 185 may be divided into four pieces to reduce eddy current noise, caused by high-frequency magnetic noise, and thermal noise, caused by free electrons of a metal, and may provide a uniform location-dependent temperature gradient. The first auxiliarythermal anchor 185 may be in thermal contact with the mainthermal anchor 170 by alitz wire 12. - A first internal 4K
heat shielding portion 124 may be in thermal contact with the first auxiliarythermal anchor 185, and may be disposed on an internal side surface of the first sensor-mountedhelmet 322. The first internal 4Kheat shielding portion 124 may be disposed to surround theSQUID sensor modules 103 a, and may include an insulation-coated metal mesh. - A first external 4K
heat shielding portion 126 may be in thermal contact with the first auxiliarythermal anchor 185, and may be disposed on an external side surface of the first sensor-mountedhelmet 322. The first external 4Kheat shielding portion 126 may be disposed to surround an external side surface of the first sensor-mountedhelmet 322. The first external 4Kheat shielding portion 126 may include an insulation-coated metal mesh. Accordingly, the firstauxiliary heat anchor 185, the first internal 4Kheat shielding portion 124, and the first external 4Kheat shielding portion 126 may be in thermal contact with themain heat anchor 170 by alitz wire 12. - A second auxiliary thermal anchor may be disposed on a lower surface of the brim of the second sensor-mounted
helmet 332. A second internal 4K heat shielding portion may be in thermal contact with the second auxiliary thermal anchor, and may be disposed on an internal side surface of the second sensor-mountedhelmet 332. The second external 4K heat shielding portion may be in thermal contact with the second auxiliary thermal anchor, and may be disposed on an external side surface of the second sensor-mounted helmet. The second auxiliary heat anchor, the second internal 4K heat shielding portion, and the second external 4K heat shielding portion may be in thermal contact with themain heat anchor 170 through alitz wire 12. -
FIG. 11 is a conceptual diagram illustrating a connection relationship between a main thermal anchor and a SQUID sensor module according to an example embodiment of the present disclosure. -
FIG. 12 is a cross-sectional view of the main thermal anchor. - Referring to
FIGS. 11 and 12 , each of the plurality of firstSQUID sensor modules 103 a may be in thermal contact with a mainthermal anchor 170 disposed on the lower surface of theinternal container 360 through alitz wire 12. Each of the plurality of secondSQUID sensor modules 103 b may be in thermal contact with the mainthermal anchor 170 disposed on the lower surface of theinternal container 360 through thelitz wire 12. - The
main heat anchor 170 may include a firstheat transfer unit 171, a secondheat transfer unit 172, a thirdheat transfer unit 173, a fourthheat transfer unit 174, a fifthheat transfer unit 175, a first thermalexpansion control unit 176, and a second thermalexpansion control unit 177. The mainthermal anchor 170 may include of a plurality of components to increases a thermal contact area while inhibiting damage to the internal container caused by thermal expansion, and thus, may efficiently cool alitz wire 12 and a SQUID sensor. - The first thermal
expansion control unit 176 may be coupled to a double groove having two radii formed on an internal side of the lower surface of the internal container, and the second thermalexpansion control unit 177 may be coupled to a double groove having two radii formed on an external side of the lower surface of the internal container. - The first
heat transfer unit 171 may be formed of oxygen-free copper, and may include afirst disc 171 a and a firstlower projection 171 b protruding from a central axis of thefirst disc 171 a to a lower surface of thefirst disc 171 a. The firstheat transfer unit 171 may further include a firstupper projection 171 c protruding from the central axis of thefirst disc 171 a to an upper surface of thefirst disc 171 a. - The second
heat transfer unit 172 may be formed of oxygen-free copper, and may include asecond disc 172 a, a second upper projection 172 b protruding from a central axis of thesecond disc 172 a to an upper surface of thesecond disc 172 a, and a secondlower projection 172 c protruding from the central axis of thesecond disc 172 a to a lower surface of thesecond disc 172 a. The second upper projection 172 b of the secondheat transfer unit 172 may include ascrew groove 172 d for coupling to the firstlower projection 171 b of the firstheat transfer unit 171. The secondlower projection 172 c of the secondheat transfer unit 172 may have a screw groove 172 e for coupling to the thirdupper projection 173 b of the thirdheat transfer unit 173. - The third
heat transfer unit 173 may be formed of oxygen-free copper, and may include athird disc 173 a, a thirdupper projection 173 b protruding from a central axis of thethird disc 173 a to an upper surface of thethird disc 173 a, and a thirdlower projection 173 c protruding from the central axis of thethird disc 173 a to a lower surface of thethird disc 173 a. The thirdlower projection 173 c of the thirdheat transfer unit 173 may have ascrew groove 173 d for coupling to the fourthupper projection 174 b of the fourthheat transfer unit 174. - The fourth
heat transfer unit 174 may be formed of oxygen-free copper, and may include a fourth disc, a fourthupper projection 174 b protruding from a central axis of the fourth disc to an upper surface of the fourth disc, and a fourth lower projection 174 c protruding from the central axis of the fourth disc to a lower surface of the fourth disc. - The fifth
heat transfer unit 175 may be formed of oxygen-free copper, and may include a C-shaped plate. The fifthheat transfer unit 175 may be coupled to the fourth lower projection 174 c of the fourthheat transfer portion 174. A lower surface of the fifthheat transfer unit 175 may be coupled to a fixing means 178. The fixing means 178 may fix and cool thelitz wire 12 connected to theSQUID sensor module 103 a. - The first thermal
expansion control unit 176 may be formed of an insulating material, or and may be inserted between thefirst disc 171 a of the firstheat transfer unit 171 and the second disc 172 b of the secondheat transfer unit 172. The first thermalexpansion control unit 176 may include the same material as the internal container. - The second thermal
expansion control unit 177 may be formed of an insulating material, and may be inserted between thethird disc 173 a of the thirdheat transfer unit 173 and thefourth disc 174 a of the fourthheat transfer unit 174. The second thermalexpansion control unit 177 may include the same material as the internal container. - The first thermal
expansion control unit 176 may include a first insulating body portion 176 a having the same diameter as a first diameter D1 of thefirst disc 171 a, a second insulating body portion 176 b embedded in a lower surface of the internal body and having a second diameter D2 greater than the first diameter D1, and a third insulating body portion 176 c having a third diameter D3 smaller than the second diameter D2. The third insulating body portion 176 c may be disposed to surround an external circumferential surface of thesecond disc 172 a. An external circumferential surface of the third insulating body portion 176 c may be provided with a screw groove. - The second thermal
expansion control unit 177 may have the same structure as the first thermalexpansion control unit 176. - When the first to fourth
heat transfer units 171 to 174 are coupled to each other, the first thermalexpansion control unit 176 and the second thermalexpansion control unit 177 may be pressed to be sealed with the internal container. In addition, thefirst disc 171 a and thefourth disc 174 a may be sealed by pressing the first thermalexpansion control unit 176 and the second thermalexpansion control unit 177. - The main
thermal anchor 170 may cool the firstSQUID sensor module 103 a and the secondSQUID sensor module 103 b through a litz wire. - Each of the first
SQUID sensor modules 103 a may be cooled by a plurality oflitz wires 12. Some of the plurality ofLitz wires 12 may be provided to a neighboring firstSQUID sensor module 103 a. The remainder of the plurality oflitz wires 12 may be in thermal contact with the mainthermal anchor 170. - Each of the first SQUID sensor modules 130 a may be cooled by six
litz wires 12. Twolitz wires 12 may be in thermal contact with the mainthermal anchor 170, and the rest fourlitz wires 12 may be connected to a neighboring firstSQUID sensor module 103 a. - Each of the first
SQUID sensor modules 103 a may be inserted into a through-hole, formed in the firstsensor mounting helmet 322, to be fixed. - The first
SQUID sensor module 103 a may have a plurality ofholes 611. Thelitz wire 12 may be inserted into theholes 611 to cool theSQUID sensor 646. -
FIG. 13A is a perspective view illustrating a SQUID sensor module according to an example embodiment of the present disclosure. -
FIG. 13B is an exploded perspective view illustrating the SQUID sensor module ofFIG. 13A . -
FIG. 13C is a cross-sectional view illustrating a SQUID sensor module according to an example embodiment of the present disclosure. - Referring to
FIGS. 13A to 13C , aSQUID sensor module 103 a/103 b may include afixed block 610 having one end fixed to a sensor-mounted helmet 122/132, abobbin 630 having one end coupled to the other end of the fixedblock 610 and provided with a groove around which a pick-upcoil 601 is wound, a bobbin fixing means 650 fixed to the other end of the fixedblock 610 through a through-hole formed in a center of thebobbin 630, a superconducting quantum interference device (SQUID) printed circuit board (PCB) 640 disposed on an upper side surface of thebobbin 630 and including aSQUID sensor 646, and a signalline connection PCB 620 inserted into an external circumferential surface of the fixedblock 610 and transferring a signal, detected by theSQUID sensor 646, to an external circuit. - The sensor-mounted helmets 122 and 132 may mount a SQUID sensor module 600, and may be disposed in a vacuum space between an external container and an internal container. The sensor-mounted helmets 122 and 132 may be formed of a non-magnetic material. The sensor-mounted helmets 122 and 132 may include a first sensor-mounted
helmet 322 and a second sensor-mountedhelmet 332 mounting a SQUID sensor module. - The fixed
block 610 may be formed of a non-magnetic material, such as G10 epoxy, in an integral type. The fixedblock 610 may be inserted into the through-hole 122 b formed in the sensor-mounted helmet to be fixed through an adhesive. The fixedblock 610 may include afixed block projection 612, a fixedblock threshold portion 614, a fixedblock body portion 616, and a fixedblock extending portion 618. The fixedblock 610 may have a plurality ofholes 611 in a central axis direction in which a litz wire for cooling is inserted. The litz wire may be inserted into each of a plurality ofholes 611 to cool theSQUID sensor 646. - The fixed
block projection 612 may have a disc shape, and may be coupled to a groove or a through-hole 122 b formed in the sensor-mounted helmet. In addition, the fixedblock projection 612 may be fixed to the through-hole through an adhesive. - The fixed
block threshold portion 614 may have a disc shape and may be continuously connected to the fixedblock projection portion 612. The fixedblock threshold portion 614 may have a greater diameter than the fixedblock projection 612. The fixedblock threshold portion 614 may have aplanar side surface 614 a. Oneside surface 614 a of the fixedblock threshold 614 may be a plane having a predetermined first vertical distance from a central axis having a cylindrical shape. The fixedblock threshold portion 614 may serve to perform an alignment in a central axis direction. A through-hole 619 may be formed in an exterior of the fixedblock threshold 614. - The fixed
block body portion 616 may be a portion coupled to the signalline connection PCB 620. The signalline connection PCB 620 may be disposed to be inserted into the external peripheral surface of the fixedblock body portion 616. The signalline connection PCB 620 may include ahole 623 on an external periphery thereof. The through-hole 619 of the fixedblock threshold 614 may be aligned with thehole 623 of the signalline connection PCB 620. The fixing means may be inserted into the through-hole 619 of the fixedblock threshold portion 614 and thehole 623 of the signalline connection PCB 620 to fix the fixedblock threshold portion 614 and the signalline connection PCB 620 to each other. An internal diameter of the signalline connection PCB 620 may be substantially the same as an external diameter of the fixedblock body portion 616. In addition, the external diameter of the signalline connection PCB 620 may be substantially the same as an external diameter of the fixedblock threshold 614. - The signal
line connection PCB 620 has a washer shape having a central through-hole therein. When the signalline connection PCB 620 is coupled to the external circumferential surface of the fixedblock 610, one side of the central through-hole may be planar so as to inhibit a rotational motion. The signalline connection PCB 620 may include afirst connector 622. Thefirst connector 622 may be a female connector. Thefirst connector 622 may be disposed on an edge of a lower surface of the signalline connection PCB 620. Aconnection terminal 624 and a wiring may be disposed on an upper surface of the signalline connection PCB 620. Theconnection terminal 624 may be connected to thefirst connector 622 through the wiring. A connection wire, connected to an external circuit, may be coupled to theconnection terminal 624. - The fixed
block body portion 616 may have a disc shape and may be continuously connected to the fixedblock threshold portion 614. The fixedblock body portion 616 may have a smaller diameter than the fixedblock threshold portion 614, and may have aplanar side surface 616 a. Oneside surface 616 a of the fixedblock body portion 616 may be a plane having a predetermined second vertical distance from the central axis having a cylindrical shape. - The fixed
block extending portion 618 may have the same diameter as the fixedblock body portion 616, and may have aplanar side surface 618 a. Theside surface 618 a may be a plane having a predetermined third vertical distance from the central axis having a cylindrical shape. The third vertical distance may be smaller than the second vertical distance. - One
planar side surface 614 a of the fixedblock threshold portion 614 and oneplanar side surface 616 a of the fixedblock body portion 616 may be connected to each other. The oneside surface 616 a of the fixedblock body 616 and the oneside surface 618 a of the fixedblock extending portion 618 may be spaced apart from each other to be parallel to each other. A vertical distance between a central axis and one side surface of the fixedblock extending portion 618 may be smaller than a vertical distance between the central axis and one side surface of the fixedblock body portion 616. - The
bobbin 630 may be formed of a non-magnetic material such as G10 epoxy. Thebobbin 630 may have a cylindrical shape. Thebobbin 630 includes a firstplanar portion 634, formed on an upper side surface having a first vertical distance from the central axis, and a secondplanar portion 634 formed on alower side surface 636 having a second vertical distance larger than the first vertical distance. Thebobbin 630 may have agroove 632 formed around a lower side surface thereof. The groove may form a closed loop. A pick-upcoil 601 may be wound around thegroove 632. Ahole 635 may be formed in the firstplanar portion 634. Thehole 635 may be coupled to a fixing means for fixing theSQUID PCB 640. TheSQUID PCB 640 may be disposed on the firstplanar portion 634. Both ends of the pick-upcoil 601 may be fixed to the secondplanar portion 636 through an adhesive. The pick-upcoil 601 may be electrically connected to theSQUID sensor 646 through aconnection line 648 formed of a superconductor material. Theconnection line 648 may include a niobium (Nb) material. - The
SQUID PCB 640 may include asecond connector 642 and aSQUID sensor 646 and disposed on aPCB substrate 644. TheSQUID sensor 646 may be in the form of a semiconductor chip. TheSQUID sensor 646 may include an input coil and a Josephson junction. TheSQUID sensor 646 may include a conductive pad for electrical connection to the pick-upcoil 601. The conductive pad may connect the pick-upcoil 601. Thesecond connector 642 may be electrically connected to another conductive pad. Thesecond connector 642 may be a pin-type male connector. Accordingly, thesecond connector 642 may be separated from or coupled to thefirst connector 622. - The pick-up
coil 601 may be a first-order axial gradiometer. Therefore, a length of a bobbin, around which the pick-upcoil 601 a is wound, may be increased. The pick-upcoil 601 may include a pair of one-turn coils continuously connected and wound in directions opposite to each other. The pick-upcoil 601 and theSQUID sensor 646 are bonded to be directly connected to each other using aconnection line 648 of a thermally treated superconducting material, and an integral-type QUID magnetometer may be manufactured. A material of the pick-upcoil 601 may be a niobium-tantalum (NbTi) wire. - The connection line of a niobium (Nb) material, used for bonding, may be subject to a vacuum heat treatment at a temperature 1900 degrees Celsius to increase ductility. Superconducting bonding may be performed using an ultrasonic wedge bonder. Both end portions of the pick-up coil may be twisted together. Accordingly, noise of the pick-up coil may be significantly reduced. The pick-up coil may be a first-order gradiometer or a magnetometer.
- The bobbin fixing means 650 may be inserted into a through-
hole 638 penetrating through a central axis of thebobbin 630. Thus, the bobbin fixing means 650 may be fixed to a lower surface of the fixedblock 610. The bobbin fixing means 650 may include a non-magnetic material such as G10 epoxy. - When the
SQUID PCB 640 malfunctions, the bobbin fixing means 650 may be removed to replace theSQUID PCB 640. In this case, thebobbin 630 and the fixedblock 610 may be separated from each other. Thus, the malfunctioning SQUID PCB may be simply replaced with a new SQUID PCB. As a result, maintenance may be facilitated. - The
SQUID sensor module 103 a/103 b may include afixed block 610 having one end fixed to a support portion, abobbin 630 having one end coupled to the other end of the fixedblock 610 and having a groove around which a pick-upcoil 601 a is wound, a bobbin fixing means fixed to the other end of the fixedblock 610 through a through-hole formed in a center of thebobbin 630, a superconducting quantum interference device (SQUID) printed circuit board (PCB) 640 including a SQUID sensor, and a signalline connection PCB 620 inserted into an external circumferential surface of the fixedblock 610 and transferring a signal, detected by the SQUID sensor, to an external circuit. -
FIG. 14 is a perspective view illustrating a SQUID sensor module according to another example embodiment of the present disclosure. - Referring to
FIGS. 3 and 14 , a first referenceSQUID sensor module 105 a may be disposed on a first sensor-mountedhelmet 322, and a second referenceSQUID sensor module 105 b may be disposed on a second sensor-mountedhelmet 332. The first referenceSQUID sensor module 105 a may be used as a sensor measuring a background magnetic field while the secondSQUID sensor module 103 b is operating. The second referenceSQUID sensor module 105 b may be used as a sensor measuring a background magnetic field while the firstSQUID sensor module 103 a is operating. - Each of the first reference
SQUID sensor module 105 a and the second referenceSQUID sensor module 105 b may be a triaxial magnetic field sensor. Each of the first referenceSQUID sensor module 105 a and the second referenceSQUID sensor module 105 b may include a first pick-upcoil 743 a detecting a magnetic field component in an x-axis direction, a second pick-upcoil 743 b detecting a magnetic field component in a y-axis direction, and a third pick-upcoil 743 c detecting a magnetic field component in a z-axis direction. Each of the first to third pick-upcoils 743 a to 743 c may be connected to theSQUID sensor 746. - The first reference
SQUID sensor module 105 a may include a cylindrical fixedblock 741 and abobbin 742 in which a pick-up coil, coupled to the fixedblock 741, is disposed. Thebobbin 742 may have a rectangular parallelepiped shape. The fixedblock 741 may have through-holes in a plurality of central-axis directions, andlitz wires 12 may be inserted into the through-holes. Thelitz wires 12 may be connected to a mainthermal anchor 170. - As described above, a magnetoencephalography (MEG) measuring apparatus according to an example embodiment may measure magnetoencephalography of children's MEG or adults' MEG according to a rotation state using a helmet for children and a helmet for adults, respectively disposed on both ends of a barrel-shaped Dewar placed horizontally in a narrow magnetically shielded room.
- A magnetoencephalography (MEG) measuring apparatus according to an example embodiment may efficiently block radiant heat using a neck portion having a double-wall structure in a barrel-shaped Dewar placed horizontally.
- A magnetoencephalography (MEG) measuring apparatus according to an example embodiment may measure children's MEG or adults' MEG according to a rotation state by placing a rotational motion unit, providing a rotational motion, on the ground in a barrel-shaped Dewar disposed horizontally.
- A magnetoencephalography (MEG) measuring apparatus according to an example embodiment may increase efficiency of a condenser or a cooler by transferring a low-temperature refrigerant to the condenser while providing a rotation motion using a coaxial dual-tube structure connecting the condenser and a Dewar to each other.
- A magnetoencephalography (MEG) measuring apparatus according to an example embodiment may employ a coil-in-vacuum structure, and thus, may decrease a distance between a SQUID sensor and a current source to increase a signal-to-noise ratio (SNR).
- A magnetoencephalography measuring apparatus according to an example embodiment of the present disclosure may include a main thermal anchor for cooling a SQUID sensor on a lower surface of an internal container storing a refrigerant. The main thermal anchor may include a plurality of components to increase a thermal contact area while inhibiting damage to the internal container caused by thermal expansion. Thus, a litz wire and the SQUID sensor may be efficiently cooled.
- Although the present disclosure and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the following claims.
Claims (39)
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KR1020200066113A KR102354391B1 (en) | 2020-06-01 | 2020-06-01 | Dual Helmets Magnetoencephalography Apparatus |
PCT/KR2021/002437 WO2021246617A1 (en) | 2020-06-01 | 2021-02-26 | Dual-helmet magnetoencephalography apparatus |
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KR20210148779A (en) | 2021-12-08 |
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